Bio

Clinical Focus


  • Endocrinology

Academic Appointments


Professional Education


  • Board Certification: Internal Medicine, American Board of Internal Medicine (1995)
  • Fellowship:Stanford University Medical Center (2002) CA
  • Fellowship:Stanford University Medical Center (1999) CA
  • Fellowship:Stanford University Medical Center (1998) CA
  • Residency:University of Connecticut-School of Medicine (1995) CT
  • Internship:University of Connecticut-School of Medicine (1993) CT
  • Medical Education:King Edward Medical University (1988) Pakistan

Publications

All Publications


  • Relationship Among 25-Hydroxyvitamin D Concentrations, Insulin Action, and Cardiovascular Disease Risk in Patients With Essential Hypertension AMERICAN JOURNAL OF HYPERTENSION Abbasi, F., Feldman, D., Caulfield, M. P., Hantash, F. M., Reaven, G. M. 2015; 28 (2): 266-272

    Abstract

    Although low plasma 25-hydroxyvitamin D (25(OH)D) concentrations have been shown to predict risk of hypertension and associated cardiovascular disease (CVD), vitamin D repletion has not consistently lowered blood pressure or decreased CVD. One possibility for this discrepancy is the presence of considerable metabolic heterogeneity in patients with hypertension. To evaluate this possibility, we quantified relationships among insulin resistance, 25(OH)D concentration, and CVD risk factor profile in patients with essential hypertension.Measurements were made of 25(OH)D concentrations, multiple CVD risk factors, and insulin resistance by the steady-state plasma glucose concentration during the insulin suppression test in 140 otherwise healthy patients with essential hypertension.As a group, the patients were overweight/obese and insulin resistant and had low 25(OH)D concentrations. The more insulin resistant the patients were, the worse the CVD risk profile was. In addition, the most insulin-resistant quartile had significantly lower 25(OH)D concentrations than the most insulin-sensitive quartile (20.3±1.4 vs. 25.8±1.4ng/ml; P = 0.005). In the entire group, 25(OH)D concentration significantly correlated with magnitude of insulin resistance (steady-state plasma glucose concentration; r = -0.20; P = 0.02).There was considerable metabolic heterogeneity and substantial difference in magnitude of conventional CVD risk factors in patients with similar degrees of blood pressure elevation. The most insulin-resistant quartile of subjects had the lowest 25(OH)D concentration and the most adverse CVD risk profile, and they may be the subset of patients with essential hypertension most likely to benefit from vitamin D repletion.

    View details for DOI 10.1093/ajh/hpu136

    View details for Web of Science ID 000349559300015

    View details for PubMedID 25138785

  • Effect of liraglutide administration and a calorie-restricted diet on lipoprotein profile in overweight/obese persons with prediabetes NUTRITION METABOLISM AND CARDIOVASCULAR DISEASES Ariel, D., Kim, S. H., Abbasi, F., Lamendola, C. A., Liu, A., Reaven, G. M. 2014; 24 (12): 1317-1322

    Abstract

    To evaluate the effects of 14 weeks of liraglutide plus modest caloric restriction on lipid/lipoprotein metabolism in overweight/obese persons with prediabetes.Volunteers with prediabetes followed a calorie-restricted diet (-500 Kcal/day) plus liraglutide (n = 23) or placebo (n = 27) for 14 weeks. The groups were similar in age (58 ± 7 vs. 58 ± 8 years) and body mass index (31.9 ± 2.8 vs. 31.9 ± 3.5 kg/m(2)). A comprehensive lipid/lipoprotein profile was obtained before and after intervention using vertical auto profile (VAP). Weight loss was greater in the liraglutide group than in the placebo group (6.9 vs. 3.3 kg, p < 0.001), as was the fall in fasting plasma glucose concentration (9.9 mg/dL vs. 0.3 mg/dL, p < 0.001). VAP analysis revealed multiple improvements in lipid/lipoprotein metabolism in liraglutide-treated compared with placebo-treated volunteers, including decreases in concentrations of total cholesterol, low-density lipoprotein cholesterol and several of its subclasses, triglyceride, and non-high-density cholesterol. The liraglutide-treated group also had a significant shift away from small, dense low-density lipoprotein-particles, as well as decreases in apolipoprotein B concentration and ratio of apolipoprotein B/apolipoprotein A-1. There were no significant changes in the lipoprotein profile in the placebo-treated group.Treatment with liraglutide plus modest calorie restriction led to enhanced weight loss, a decrease in fasting plasma glucose concentration, and improvement in multiple aspects of lipid/lipoprotein metabolism associated with increased cardiovascular disease (CVD) risk. The significant clinical benefit associated with liraglutide-assisted weight loss in a group at high risk for CVD - obese/overweight individuals with prediabetes - as seen in our pilot study, suggests that this approach deserves further study.

    View details for DOI 10.1016/j.numecd.2014.06.010

    View details for Web of Science ID 000348043200008

  • Effect of Salsalate on Insulin Action, Secretion, and Clearance in Nondiabetic, Insulin-Resistant Individuals: A Randomized, Placebo-Controlled Study DIABETES CARE Kim, S. H., Liu, A., Ariel, D., Abbasi, F., Lamendola, C., Grove, K., Tomasso, V., Ochoa, H., Reaven, G. 2014; 37 (7): 1944-1950

    View details for DOI 10.2337/dc13-2977

    View details for Web of Science ID 000338020400030

  • Impact of Type 2 Diabetes Susceptibility Variants on Quantitative Glycemic Traits Reveals Mechanistic Heterogeneity DIABETES Dimas, A. S., Lagou, V., Barker, A., Knowles, J. W., Maegi, R., Hivert, M., Benazzo, A., Rybin, D., Jackson, A. U., Stringham, H. M., Song, C., Fischer-Rosinsky, A., Boesgaard, T. W., Grarup, N., Abbasi, F. A., Assimes, T. L., Hao, K., Yang, X., Lecoeur, C., Barroso, I., Bonnycastle, L. L., Boettcher, Y., Bumpstead, S., Chines, P. S., Erdos, M. R., Graessler, J., Kovacs, P., Morken, M. A., Narisu, N., Payne, F., Stancakova, A., Swift, A. J., Toenjes, A., Bornstein, S. R., Cauchi, S., Froguel, P., Meyre, D., Schwarz, P. E., Haering, H., Smith, U., Boehnke, M., Bergman, R. N., Collins, F. S., Mohlke, K. L., Tuomilehto, J., Quertemous, T., Lind, L., Hansen, T., Pedersen, O., Walker, M., Pfeiffer, A. F., Spranger, J., Stumvoll, M., Meigs, J. B., Wareham, N. J., Kuusisto, J., Laakso, M., Langenberg, C., Dupuis, J., Watanabe, R. M., Florez, J. C., Ingelsson, E., McCarthy, M. I., Prokopenko, I. 2014; 63 (6): 2158-2171

    Abstract

    Patients with established type 2 diabetes display both beta-cell dysfunction and insulin resistance. To define fundamental processes leading to the diabetic state, we examined the relationship between type 2 diabetes risk variants at 37 established susceptibility loci and indices of proinsulin processing, insulin secretion and insulin sensitivity. We included data from up to 58,614 non-diabetic subjects with basal measures, and 17,327 with dynamic measures. We employed additive genetic models with adjustment for sex, age and BMI, followed by fixed-effects inverse variance meta-analyses. Cluster analyses grouped risk loci into five major categories based on their relationship to these continuous glycemic phenotypes. The first cluster (PPARG, KLF14, IRS1, GCKR) was characterized by primary effects on insulin sensitivity. The second (MTNR1B, GCK) featured risk alleles associated with reduced insulin secretion and fasting hyperglycemia. ARAP1 constituted a third cluster characterized by defects in insulin processing. A fourth cluster (including TCF7L2, SLC30A8, HHEX/IDE, CDKAL1, CDKN2A/2B) was defined by loci influencing insulin processing and secretion without detectable change in fasting glucose. The final group contained twenty risk loci with no clear-cut associations to continuous glycemic traits. By assembling extensive data on continuous glycemic traits, we have exposed the diverse mechanisms whereby type 2 diabetes risk variants impact disease predisposition.

    View details for DOI 10.2337/db13-0949

    View details for Web of Science ID 000336643900039

  • Evaluation of fasting plasma insulin concentration as an estimate of insulin action in nondiabetic individuals: comparison with the homeostasis model assessment of insulin resistance (HOMA-IR) ACTA DIABETOLOGICA Abbasi, F., Okeke, Q., Reaven, G. M. 2014; 51 (2): 193-197

    Abstract

    Insulin-mediated glucose disposal varies severalfold in apparently healthy individuals, and approximately one-third of the most insulin resistant of these individuals is at increased risk to develop various adverse clinical syndromes. Since direct measurements of insulin sensitivity are not practical in a clinical setting, several surrogate estimates of insulin action have been proposed, including fasting plasma insulin (FPI) concentration and the homeostasis model assessment of insulin resistance (HOMA-IR) calculated by a formula employing fasting plasma glucose (FPG) and FPI concentrations. The objective of this study was to compare FPI as an estimate of insulin-mediated glucose disposal with values generated by HOMA-IR in 758 apparently healthy nondiabetic individuals. Measurements were made of FPG, FPI, triglyceride (TG), and high-density lipoprotein cholesterol (HDL-C) concentrations, and insulin-mediated glucose uptake was quantified by determining steady-state plasma glucose (SSPG) concentration during the insulin suppression test. FPI and HOMA-IR were highly correlated (r = 0.98, P < 0.001). The SSPG concentration also correlated to a similar degree (P < 0.001) with FPI (r = 0.60) and HOMA-IR (r = 0.64). Furthermore, the relationship between FPI and TG (r = 0.35) and HDL-C (r = -0.40) was comparable to that between HOMA-IR and TG (r = 0.39) and HDL-C (r = -0.41). In conclusion, FPI and HOMA-IR are highly correlated in nondiabetic individuals, with each estimate accounting for ~40 % of the variability (variance) in a direct measure of insulin-mediated glucose disposal. Calculation of HOMA-IR does not provide a better surrogate estimate of insulin action, or of its associated dyslipidemia, than measurement of FPI.

    View details for DOI 10.1007/s00592-013-0461-2

    View details for Web of Science ID 000334054200003

    View details for PubMedID 23420066

  • Pancreatic beta cell function following liraglutide-augmented weight loss in individuals with prediabetes: analysis of a randomised, placebo-controlled study DIABETOLOGIA Kim, S. H., Liu, A., Ariel, D., Abbasi, F., Lamendola, C., Grove, K., Tomasso, V., Reaven, G. 2014; 57 (3): 455-462

    Abstract

    Liraglutide can modulate insulin secretion by directly stimulating beta cells or indirectly through weight loss and enhanced insulin sensitivity. Recently, we showed that liraglutide treatment in overweight individuals with prediabetes (impaired fasting glucose and/or impaired glucose tolerance) led to greater weight loss (-7.7% vs -3.9%) and improvement in insulin resistance compared with placebo. The current study evaluates the effects on beta cell function of weight loss augmented by liraglutide compared with weight loss alone.This was a parallel, randomised study conducted in a single academic centre. Both participants and study administrators were blinded to treatment assignment. Individuals who were 40-70 years old, overweight (BMI 27-40 kg/m(2)) and with prediabetes were randomised (via a computerised system) to receive liraglutide (n = 35) or matching placebo (n = 33), and 49 participants were analysed. All were instructed to follow an energy-restricted diet. Primary outcome was insulin secretory function, which was evaluated in response to graded infusions of glucose and day-long mixed meals.Liraglutide treatment (n = 24) significantly (p ≤ 0.03) increased the insulin secretion rate (% mean change [95% CI]; 21% [12, 31] vs -4% [-11, 3]) and pancreatic beta cell sensitivity to intravenous glucose (229% [161, 276] vs -0.5% (-15, 14]), and decreased insulin clearance rate (-3.5% [-11, 4] vs 8.2 [0.2, 16]) as compared with placebo (n = 25). The liraglutide-treated group also had significantly (p ≤ 0.03) lower day-long glucose (-8.2% [-11, -6] vs -0.1 [-3, 2]) and NEFA concentrations (-14 [-20, -8] vs -2.1 [-10, 6]) following mixed meals, whereas day-long insulin concentrations did not significantly differ as compared with placebo. In a multivariate regression analysis, weight loss was associated with a decrease in insulin secretion rate and day-long glucose and insulin concentrations in the placebo group (p ≤ 0.05), but there was no association with weight loss in the liraglutide group. The most common side effect of liraglutide was nausea.A direct stimulatory effect on beta cell function was the predominant change in liraglutide-augmented weight loss. These changes appear to be independent of weight loss.ClinicalTrials.gov NCT01784965 FUNDING: The study was funded by the ADA.

    View details for DOI 10.1007/s00125-013-3134-3

    View details for Web of Science ID 000331558400003

    View details for PubMedID 24326527

  • Reply to DN Polesel et al. American journal of clinical nutrition Liu, A., Reaven, G. M., Abbasi, F. 2013; 98 (6): 1593-?

    View details for DOI 10.3945/ajcn.113.072876

    View details for PubMedID 24259357

  • Benefits of Liraglutide Treatment in Overweight and Obese Older Individuals With Prediabetes DIABETES CARE Kim, S. H., Abbasi, F., Lamendola, C., Liu, A., Ariel, D., Schaaf, P., Grove, K., Tomasso, V., Ochoa, H., Liu, Y. V., Chen, Y. I., Reaven, G. 2013; 36 (10): 3276-3282

    Abstract

    OBJECTIVEThe aim was to evaluate the ability of liraglutide to augment weight loss and improve insulin resistance, cardiovascular disease (CVD) risk factors, and inflammation in a high-risk population for type 2 diabetes (T2DM) and CVD.RESEARCH DESIGN AND METHODSWe randomized 68 older individuals (mean age, 58 ± 8 years) with overweight/obesity and prediabetes to this double-blind study of liraglutide 1.8 mg versus placebo for 14 weeks. All subjects were advised to decrease calorie intake by 500 kcal/day. Peripheral insulin resistance was quantified by measuring the steady-state plasma glucose (SSPG) concentration during the insulin suppression test. Traditional CVD risk factors and inflammatory markers also were assessed.RESULTSEleven out of 35 individuals (31%) assigned to liraglutide discontinued the study compared with 6 out of 33 (18%) assigned to placebo (P = 0.26). Subjects who continued to use liraglutide (n = 24) lost twice as much weight as those using placebo (n = 27; 6.8 vs. 3.3 kg; P < 0.001). Liraglutide-treated subjects also had a significant improvement in SSPG concentration (-3.2 vs. 0.2 mmol/L; P < 0.001) and significantly (P ≤ 0.04) greater lowering of systolic blood pressure (-8.1 vs. -2.6 mmHg), fasting glucose (-0.5 vs. 0 mmol/L), and triglyceride (-0.4 vs. -0.1 mmol/L) concentration. Inflammatory markers did not differ between the two groups, but pulse increased after liraglutide treatment (6.4 vs. -0.9 bpm; P = 0.001).CONCLUSIONSThe addition of liraglutide to calorie restriction significantly augmented weight loss and improved insulin resistance, systolic blood pressure, glucose, and triglyceride concentration in this population at high risk for development of T2DM and CVD.

    View details for DOI 10.2337/dc13-0354

    View details for Web of Science ID 000324749500073

  • Beyond fasting plasma glucose: The association between coronary heart disease risk and postprandial glucose, postprandial insulin and insulin resistance in healthy, nondiabetic adults METABOLISM-CLINICAL AND EXPERIMENTAL Bhat, S. L., Abbasi, F. A., Blasey, C., Reaven, G. M., Kim, S. H. 2013; 62 (9): 1223-1226

    Abstract

    Prediabetes is defined by elevations of plasma glucose concentration, and is aimed at identifying individuals at increased risk of type 2 diabetes and coronary heart disease (CHD). However, since these individuals are also insulin resistant and hyperinsulinemic, we evaluated the association between several facets of carbohydrate metabolism and CHD risk profile in apparently healthy, nondiabetic individuals.Plasma glucose and insulin concentrations were measured before and at hourly intervals for eight hours after two test meals in 281 nondiabetic individuals. Insulin action was quantified by determining the steady-state plasma glucose (SSPG) concentration during the insulin suppression test. CHD risk was assessed by measurements of blood pressure and fasting lipoprotein profile.For purposes of analysis, the population was divided into tertiles, and the results demonstrated that the greater the 1) fasting plasma glucose (FPG) concentration, 2) incremental plasma insulin response to meals, and 3) SSPG concentration, the more adverse the CHD risk profile (p<0.05). In contrast, the CHD risk profile did not significantly worsen with increases in the incremental plasma glucose response to meals.In nondiabetic individuals, higher FPG concentrations, accentuated daylong incremental insulin responses to meals, and greater degrees of insulin resistance are each associated with worse CHD risk profile (higher blood pressures, higher triglycerides, and lower high density lipoprotein cholesterol concentrations). Interventional efforts aimed at decreasing CHD in such individuals should take these abnormalities into consideration.

    View details for DOI 10.1016/j.metabol.2013.04.012

    View details for Web of Science ID 000324151800004

  • Cardiometabolic risk factors and obesity: does it matter whether BMI or waist circumference is the index of obesity? AMERICAN JOURNAL OF CLINICAL NUTRITION Abbasi, F., Blasey, C., Reaven, G. M. 2013; 98 (3): 637-640

    Abstract

    It has been suggested that the cardiometabolic risk associated with excess adiposity is particularly related to central obesity.The objective was to compare the associations between cardiometabolic risk of apparently healthy individuals and measures of central obesity [waist circumference (WC)] and overall obesity [body mass index (BMI)].In this cross-sectional, observational study, 492 subjects (306 women and 303 non-Hispanic whites) were classified by BMI (in kg/m(2)) as normal weight (BMI <25) or overweight/obese (BMI = 25.0-34.9) and as having an abnormal WC (≥80 cm in women and ≥94 cm in men) or a normal WC (<80 cm in women and <94 cm in men). Measurements were also made of the cardiometabolic risk factors: age, systolic blood pressure (SBP), and fasting plasma glucose (FPG), triglyceride, and high-density lipoprotein (HDL)-cholesterol concentrations. Associations among cardiometabolic risk factors and BMI and WC were evaluated with Pearson correlations.There was a considerable overlap in the normal and abnormal categories of BMI and WC, and ∼81% of the subjects had both an abnormal BMI and WC. In women, BMI and WC correlated with SBP (r = 0.30 and 0.19, respectively), FPG (r = 0.25 and 0.22, respectively), triglycerides (r = 0.17 and 0.20, respectively), and HDL cholesterol (r = -0.23 and -0.20, respectively) (P < 0.01 for all). In men, BMI and WC also correlated with SBP (r = 0.22 and 0.22, respectively), FPG (r = 0.22 and 0.25, respectively), triglycerides (r = 0.21 and 0.18, respectively), and HDL cholesterol (r = -0.20 and -0.13, respectively) [P < 0.05 for all, except for the association of WC with HDL cholesterol (P = 0.08)].Most individuals with an abnormal BMI also have an abnormal WC. Both indexes of excess adiposity are positively associated with SBP, FPG, and triglycerides and inversely associated with HDL cholesterol.

    View details for DOI 10.3945/ajcn.112.047506

    View details for Web of Science ID 000323532700003

    View details for PubMedID 23885045

  • Genetic Variants Associated With Glycine Metabolism and Their Role in Insulin Sensitivity and Type 2 Diabetes DIABETES Xie, W., Wood, A. R., Lyssenko, V., Weedon, M. N., Knowles, J. W., Alkayyali, S., Assimes, T. L., Quertermous, T., Abbasi, F., Paananen, J., Haering, H., Hansen, T., Pedersen, O., Smith, U., Laakso, M., Dekker, J. M., Nolan, J. J., Groop, L., Ferrannini, E., Adam, K., Gall, W. E., Frayling, T. M., Walker, M. 2013; 62 (6): 2141-2150

    Abstract

    Circulating metabolites associated with insulin sensitivity may represent useful biomarkers, but their causal role in insulin sensitivity and diabetes is less certain. We previously identified novel metabolites correlated with insulin sensitivity measured by the hyperinsulinemic-euglycemic clamp. The top-ranking metabolites were in the glutathione and glycine biosynthesis pathways. We aimed to identify common genetic variants associated with metabolites in these pathways and test their role in insulin sensitivity and type 2 diabetes. With 1,004 nondiabetic individuals from the RISC study, we performed a genome-wide association study (GWAS) of 14 insulin sensitivity-related metabolites and one metabolite ratio. We replicated our results in the Botnia study (n = 342). We assessed the association of these variants with diabetes-related traits in GWAS meta-analyses (GENESIS [including RISC, EUGENE2, and Stanford], MAGIC, and DIAGRAM). We identified four associations with three metabolites-glycine (rs715 at CPS1), serine (rs478093 at PHGDH), and betaine (rs499368 at SLC6A12; rs17823642 at BHMT)-and one association signal with glycine-to-serine ratio (rs1107366 at ALDH1L1). There was no robust evidence for association between these variants and insulin resistance or diabetes. Genetic variants associated with genes in the glycine biosynthesis pathways do not provide consistent evidence for a role of glycine in diabetes-related traits.

    View details for DOI 10.2337/db12-0876

    View details for Web of Science ID 000319845000047

    View details for PubMedID 23378610

  • Measurement of insulin-mediated glucose uptake: Direct comparison of the modified insulin suppression test and the euglycemic, hyperinsulinemic clamp METABOLISM-CLINICAL AND EXPERIMENTAL Knowles, J. W., Assimes, T. L., Tsao, P. S., Natali, A., Mari, A., Quertermous, T., Reaven, G. M., Abbasi, F. 2013; 62 (4): 548-553

    Abstract

    Two direct measurements of peripheral insulin sensitivity are the M value derived from the euglycemic, hyperinsulinemic clamp (EC) and the steady-state plasma glucose (SSPG) concentration derived from the insulin suppression test (IST). Prior work suggests that these measures are highly correlated, but the agreement between them is unknown. To determine the agreement between SSPG and M and to develop transformation equations to convert SSPG to M and vice versa, we directly compared these two measurements in the same individuals.A total of 15 nondiabetic subjects (9 women and 6 men) underwent both an EC and a modified version of the IST within a median interval of 5days. We performed standard correlation metrics of the two measures and developed transformation regression equations for the two measures.The mean±SD age of the subjects was 57±7years and body mass index, 27.7±3.9kg/m(2). The median (interquartile range) SSPG concentration was 6.7 (5.1, 9.8) mmol/L and M value, 49.6 (28.9, 64.2) μmol/min/kg-LBM. There was a highly significant correlation between SSPG and M (r=-0.87, P <0.001). The relationship was best fit by regression models with exponential/logarithmic functions (R(2)=0.85). Bland-Altman plots demonstrated an excellent agreement between these measures of insulin action.The SSPG and M are highly related measures of insulin sensitivity and the results provide the means to directly compare the two measurements.

    View details for DOI 10.1016/j.metabol.2012.10.002

    View details for Web of Science ID 000317530800010

  • Body mass index and waist circumference associate to a comparable degree with insulin resistance and related metabolic abnormalities in South Asian women and men DIABETES & VASCULAR DISEASE RESEARCH Abbasi, F., Malhotra, D., Mathur, A., Reaven, G. M., Molina, C. R. 2012; 9 (4): 296-300

    Abstract

    The aim of this study was to test the hypothesis that body mass index (BMI) and waist circumference (WC) associate to a comparable degree with insulin resistance and cardiometabolic risk factors in South Asians.We measured blood pressure and fasting glucose, insulin, triglyceride, high-density lipoprotein cholesterol (HDL-C), high-sensitivity C-reactive protein (hs-CRP), and fibrinogen and calculated the homeostasis model assessment of insulin resistance (HOMA-IR) in a community-based sample of 923 nondiabetic South Asians.BMI and WC were highly correlated in both genders (r = 0.82 and 0.87). The relationship between BMI and values of blood pressure, glucose, insulin, HOMA-IR, triglyceride, HDL-C, hs-CRP, and fibrinogen was comparable to that between WC and these variables. Fasting insulin and HOMA-IR correlated most strongly with BMI (r = 0.49 to 0.56) and WC (r = 0.52 to 0.59).These results show that BMI and WC associate to a comparable degree with estimates of insulin resistance and related metabolic abnormalities in South Asians.

    View details for DOI 10.1177/1479164111433578

    View details for Web of Science ID 000309799300007

    View details for PubMedID 22278736

  • Comparison of two methods using plasma triglyceride concentration as a surrogate estimate of insulin action in nondiabetic subjects: triglycerides x glucose versus triglyceride/high-density lipoprotein cholesterol METABOLISM-CLINICAL AND EXPERIMENTAL Abbasi, F., Reaven, G. M. 2011; 60 (12): 1673-1676

    Abstract

    The objective was to compare relationships between insulin-mediated glucose uptake and surrogate estimates of insulin action, particularly those using fasting triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) concentrations. Insulin-mediated glucose uptake was quantified by determining the steady-state plasma glucose (SSPG) concentration during the insulin suppression test in 455 nondiabetic subjects. Fasting TG, HDL-C, glucose, and insulin concentrations were measured; and calculations were made of the following: (1) plasma concentration ratio of TG/HDL-C, (2) TG × fasting glucose (TyG index), (3) homeostasis model assessment of insulin resistance, and (4) insulin area under the curve (insulin-AUC) during a glucose tolerance test. Insulin-AUC correlated most closely with SSPG (r ? 0.75, P < .001), with lesser but comparable correlations between SSPG and TG/HDL-C ratio, TyG index, homeostasis model assessment of insulin resistance, and fasting TG and insulin (r ? 0.60, P < .001). Calculations of TG/HDL-C ratio and TyG index correlated with SSPG concentration to a similar degree, and the relationships were comparable to estimates using fasting insulin. The strongest relationship was between SSPG and insulin-AUC.

    View details for DOI 10.1016/j.metabol.2011.04.006

    View details for Web of Science ID 000297528400005

    View details for PubMedID 21632070

  • Preferential Fat Deposition in Subcutaneous Versus Visceral Depots Is Associated with Insulin Sensitivity JOURNAL OF CLINICAL ENDOCRINOLOGY & METABOLISM McLaughlin, T., Lamendola, C., Liu, A., Abbasi, F. 2011; 96 (11): E1756-E1760

    Abstract

    Studies on the relationship between regional fat and insulin resistance yield mixed results. Our objective was to determine whether regional fat distribution, independent of obesity, is associated with insulin resistance.Subjects included 115 healthy, overweight/moderately obese adults with body mass index (BMI) 25-36.9 kg/m(2) who met predetermined criteria for being insulin resistant (IR) or insulin sensitive (IS) based on the modified insulin suppression test. Computerized tomography was used to quantify visceral adipose tissue (VAT), sc adipose tissue (SAT), and thigh adipose tissue. Fat mass in each depot was compared according to IR/IS group, adjusting for BMI and sex.Despite nearly identical mean BMI in the IR vs. IS groups, VAT and %VAT were significantly higher in the IR group, whereas SAT, %SAT, and thigh sc fat were significantly lower. In logistic regression analysis, each sd increase in VAT increased the odds of being IR by 80%, whereas each increase in SAT decreased the odds by 48%; each increase in thigh fat decreased the odds by 59% and retained significance after adjusting for other depots. When grouped by VAT tertile, IS vs. IR individuals had significantly more SAT. There was no statistically significant interaction between sex and these relationships.These data demonstrate that after adjustment for BMI and VAT mass, sc abdominal and thigh fat are protective for insulin resistance, whereas VAT, after adjustment for SAT and BMI, has the opposite effect. Whether causal in nature or a marker of underlying pathology, these results clarify that regional distribution of fat-favoring sc depots is associated with lower risk for insulin resistance.

    View details for DOI 10.1210/jc.2011-0615

    View details for Web of Science ID 000296750600005

    View details for PubMedID 21865361

  • Plasma glucose and insulin responses to mixed meals: Impaired fasting glucose re-visited DIABETES & VASCULAR DISEASE RESEARCH BHAT, S. L., Abbasi, F., Blasey, C., Reaven, G. M., Kim, S. H. 2011; 8 (4): 271-275

    Abstract

    In individuals with varying glucose tolerance, glucose and insulin comparisons are usually made based on response to oral glucose challenge. However, an oral glucose tolerance test may not reflect daylong glucose and insulin excursions in response to meals. To better understand individuals with impaired fasting glucose (IFG), we compared insulin action as well as plasma glucose and insulin responses to mixed meals in individuals with normal fasting glucose (NFG; n = 141) and IFG (n = 148) concentrations.Insulin action was quantified by determining steady-state plasma glucose (SSPG) concentrations during the insulin suppression test. Plasma glucose and insulin concentrations were measured before and hourly after two mixed meals.SSPG concentrations were significantly higher in the IFG group (11.8 ± 3.6 vs. 9.1 ± 3.8 mmol/l). Mean hourly daylong glucose (6.4 ± 0.07 vs. 5.5 ± 0.04 mmol/l) and insulin (390 ± 20 vs. 279 ± 15 pmol/l) concentrations were also higher in those with IFG (p < 0.001). Daylong incremental meal-stimulated glucose response, however, was comparable (p = 0.77) in the two groups, whereas the incremental insulin response was 44% higher in the IFG group.Although individuals are currently defined as having IFG based on fasting plasma glucose concentration, our data show that these individuals with IFG also are insulin resistant and have higher daylong insulin concentrations.

    View details for DOI 10.1177/1479164111421036

    View details for Web of Science ID 000296976700004

    View details for PubMedID 21933842

  • Adiposity indices in the prediction of metabolic abnormalities associated with cardiovascular disease in non-diabetic adults NUTRITION METABOLISM AND CARDIOVASCULAR DISEASES Liu, A., Abbasi, F., Reaven, G. M. 2011; 21 (8): 553-560

    Abstract

    The prevalence of insulin resistance and cardiovascular disease (CVD) increases with degree of obesity. Whether measurements of generalized and abdominal obesity differ in the ability to predict changes associated with increased CVD risk is widely debated. We compared the prevalence of metabolic abnormalities in 275 women and 204 men stratified by categories of body mass index (BMI) and waist circumference (WC), and assessed the ability of these adiposity indices in combination with metabolic risk variables to predict insulin resistance.Healthy, non-diabetic volunteers underwent measurements of BMI, WC, blood pressure, fasting plasma glucose (FPG), lipoprotein concentrations, and direct quantification of insulin-mediated glucose uptake. Insulin resistance was defined as the top tertile of steady-state plasma glucose (SSPG) concentrations. BMI and WC were highly correlated (P < 0.001) in both women and men. Abnormal SSPG and triglyceride concentrations were associated with increasing adiposity by either index in both genders. Among women, abnormal FPG and high density lipoprotein cholesterol (HDL-C) concentrations were associated with increasing BMI and WC. In men, abnormal HDL-C was associated with increasing BMI only. Elevated systolic blood pressure (SBP) was associated with increasing BMI in both genders. The odds of insulin resistance were greatest in women with elevated FPG and triglycerides (4.5-fold). In men, the best predictors were BMI and SBP, and WC and HDL-C (3-fold).BMI is at least comparable to WC in stratifying individuals for prevalence of metabolic abnormalities associated with increased CVD risk and predicting insulin resistance.

    View details for DOI 10.1016/j.numecd.2009.12.009

    View details for Web of Science ID 000293596800003

    View details for PubMedID 20304617

  • Estimates of Insulin Secretory Function in Apparently Healthy Volunteers Vary as a Function of How the Relevant Variables Are Quantified CLINICAL CHEMISTRY Johns, B. R., Abbasi, F., Reaven, G. M. 2011; 57 (4): 627-632

    Abstract

    Several surrogate estimates have been used to define relationships between insulin action and pancreatic ?-cell function in healthy individuals. Because it is unclear how conclusions about insulin secretory function depend on specific estimates used, we evaluated the effect of different approaches to measurement of insulin action and secretion on observations of pancreatic ?-cell function in individuals whose fasting plasma glucose (FPG) was <7.0 mmol/L (126 mg/dL).We determined 2 indices of insulin secretion [homeostasis model assessment of ?-cell function (HOMA-?) and daylong insulin response to mixed meals], insulin action [homeostasis model assessment of insulin resistance (HOMA-IR) and steady-state plasma glucose (SSPG) concentration during the insulin suppression test], and degree of glycemia [fasting plasma glucose (FPG) and daylong glucose response to mixed meals] in 285 individuals with FPG <7.0 mmol/L. We compared the relationship between the 2 measures of insulin secretion as a function of the measures of insulin action and degree of glycemia.Assessment of insulin secretion varied dramatically as a function of which of the 2 methods was used and which measure of insulin resistance or glycemia served as the independent variable. For example, the correlation between insulin secretion (HOMA-?) and insulin resistance varied from an r value of 0.74 (when HOMA-IR was used) to 0.22 (when SSPG concentration was used).Conclusions about ?-cell function in nondiabetic individuals depend on the measurements used to assess insulin action and insulin secretion. Viewing estimates of insulin secretion in relationship to measures of insulin resistance and/or degree of glycemia does not mean that an unequivocal measure of pancreatic ?-cell function has been obtained.

    View details for DOI 10.1373/clinchem.2010.152744

    View details for Web of Science ID 000288854000017

    View details for PubMedID 21296973

  • Insulin resistance and cardiovascular disease risk factors in subjects with prehypertension DIABETES & VASCULAR DISEASE RESEARCH Knobler, H., Abbasi, F., Lamendola, C., Reaven, G. M. 2011; 8 (1): 43-46

    Abstract

    Prehypertension is considered to be associated with increased cardiovascular disease (CVD), and some data suggest that insulin resistance is common in this group. The goal of this study was to quantify insulin action by determining the steady-state plasma glucose (SSPG) concentration during the insulin suppression test in apparently healthy individuals with prehypertension (n=126) and to elucidate the relationship between insulin action and CVD risk.We found a marked heterogeneity in insulin sensitivity in the prehypertension group, and when we divided the population into insulin-sensitive, insulin-resistant and intermediate groups, there were significant (p<0.01) increases in plasma glucose and triglyceride concentrations and decreases in high-density lipoprotein cholesterol concentrations with progressive degrees of insulin resistance. These data show that at least one-third of patients with prehypertension are insulin resistant, display the accompanying metabolic abnormalities, and merit enhanced surveillance and intensive efforts at therapeutic intervention to prevent CVD.

    View details for DOI 10.1177/1479164110396919

    View details for Web of Science ID 000287469500006

    View details for PubMedID 21262870

  • What is the effect of rosiglitazone treatment on insulin secretory function in insulin-resistant individuals? It depends on how you measure It METABOLISM-CLINICAL AND EXPERIMENTAL Abbasi, F., Lamendola, C., Reaven, G. M. 2011; 60 (1): 57-62

    Abstract

    The goal of this study was to compare methods used to quantify the effect of rosiglitazone (RSG) on insulin secretory function, particularly estimates based on changes in fasting plasma glucose and insulin concentration vs daylong insulin responses to meals. To do this, we compared these measures of insulin secretion before and 3 months after RSG treatment in insulin-resistant individuals, subdivided into nondiabetic subjects (n = 29) and patients with type 2 diabetes mellitus (2DM) (n = 22). Insulin resistance was quantified by determining the steady-state plasma glucose concentration during the insulin suppression test and insulin secretory function by homeostasis model assessment of ?-cell function (HOMA-?) and the total integrated daylong plasma insulin responses to mixed meals (insulin area under the curve). Baseline fasting and daylong plasma glucose concentrations were higher (P < .001) in patients with 2DM, associated with lower HOMA-? values (P < .001). However, neither fasting nor daylong insulin concentrations after mixed meals differed in the 2 groups. Insulin sensitivity improved (P < .001) after RSG administration, with decreases of 31% ± 23% and 21% ± 14% in steady-state plasma glucose concentration in nondiabetic and diabetic subjects, respectively. Although fasting and daylong plasma glucose and insulin concentrations fell (P < .001) in both groups of RSG-treated individuals, HOMA-? decreased in nondiabetic subjects and did not change in those with 2DM. In conclusion, RSG administration improved insulin sensitivity in both groups, associated with lower fasting and daylong glucose concentrations. Fasting and daylong insulin concentrations were also lower in both groups of RSG-treated subjects, but the values of HOMA-? indicated either a decrease (nondiabetics) or no change (diabetics) in insulin secretory function. These results suggest that measurements of HOMA-? may not provide a complete view of insulin secretory function, either when comparing diabetic with nondiabetic individuals or when assessing the response to RSG treatment in insulin-resistant individuals.

    View details for DOI 10.1016/j.metabol.2010.02.015

    View details for Web of Science ID 000285441300006

    View details for PubMedID 20356610

  • Glucose-Stimulated Insulin Secretion in Gastric Bypass Patients with Hypoglycemic Syndrome: No Evidence for Inappropriate Pancreatic beta-cell Function OBESITY SURGERY Kim, S. H., Abbasi, F., Lamendola, C., Reaven, G. M., McLaughlin, T. 2010; 20 (8): 1110-1116

    Abstract

    Roux-en-Y gastric bypass surgery (RYGB) has been associated with a hypoglycemic syndrome characterized by postprandial hypoglycemia and hyperinsulinemia. The syndrome is believed to occur due to insulin hypersecretion from either pancreatic beta-cell hyperplasia or hyperfunction.Eight RYGB patients with hypoglycemic syndrome had insulin secretion rates determined during a 240-min graded intravenous glucose infusion. They were compared to 34 nondiabetic, nonsurgical individuals who were divided based on their insulin sensitivity status as measured by the insulin suppression test: insulin-sensitive (n = 8), insulin intermediate (n = 7), and insulin-resistant (n = 19).RYGB patients had insulin concentrations and HOMA-IR similar to the insulin-sensitive reference group. In addition, integrated insulin secretion rates were comparable to the insulin-sensitive group and significantly lower than the insulin intermediate (p

    View details for DOI 10.1007/s11695-010-0183-2

    View details for Web of Science ID 000280746100304

    View details for PubMedID 20665189

  • Comparison of Surrogate and Direct Measurement of Insulin Resistance in Chronic Hepatitis C Virus Infection: Impact of Obesity and Ethnicity HEPATOLOGY Lam, K. D., Bacchetti, P., Abbasi, F., Ayala, C. E., Loeb, S. M., Shah, V., Wen, M. J., Reaven, G. M., Maher, J. J., Khalili, M. 2010; 52 (1): 38-46

    Abstract

    Studies using surrogate estimates show high prevalence of insulin resistance in hepatitis C infection. This study prospectively evaluated the correlation between surrogate and directly measured estimates of insulin resistance and the impact of obesity and ethnicity on this relationship. Eighty-six nondiabetic, noncirrhotic patients with hepatitis C virus (age = 48 +/- 7 years, 74% male, 44% white, 22% African American, 26% Latino, 70% genotype 1) were categorized into normal-weight (body mass index [BMI] < 25, n = 30), overweight (BMI = 25-29.9, n = 38), and obese (BMI > or = 30, n = 18). Insulin-mediated glucose uptake was measured by steady-state plasma glucose (SSPG) concentration during a 240-minute insulin suppression test. Surrogate estimates included: fasting glucose and insulin, glucose/insulin, homeostasis model assessment (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), insulin (I-AUC) and glucose (G-AUC) area under the curve during oral glucose tolerance test, and the Belfiore and Stumvoll indexes. All surrogate estimates correlated with SSPG, but the magnitude of correlation varied (r = 0.30-0.64). The correlation coefficients were highest in the obese. I-AUC had the highest correlation among all ethnic and weight groups (r = 0.57-0.77). HOMA-IR accounted for only 15% of variability in SSPG in the normal weight group. The common HOMA-IR cutoff of < or =3 to define insulin resistance had high misclassification rates especially in the overweight group independent of ethnicity. HOMA-IR > 4 had the lowest misclassification rate (75% sensitivity, 88% specificity). Repeat HOMA-IR measurements had higher within-person variation in the obese (standard deviation = 0.77 higher than normal-weight, 95% confidence interval = 0.25-1.30, P = 0.005).Because of limitations of surrogate estimates, caution should be used in interpreting data evaluating insulin resistance especially in nonobese, nondiabetic patients with HCV.

    View details for DOI 10.1002/hep.23670

    View details for Web of Science ID 000279409200007

    View details for PubMedID 20578127

  • Detailed Physiologic Characterization Reveals Diverse Mechanisms for Novel Genetic Loci Regulating Glucose and Insulin Metabolism in Humans Ingelsson, E., Langenberg, C., Hivert, M., Prokopenko, I., Lyssenko, V., Dupuis, J., Maegi, R., Sharp, S., Jackson, A. U., Assimes, T. L., Shrader, P., Knowles, J. W., Zethelius, B., Abbasi, F. A., Bergman, R. N., Bergmann, A., Berne, C., Boehnke, M., Bonnycastle, L. L., Bornstein, S. R., Buchanan, T. A., Bumpstead, S. J., Boettcher, Y., Chines, P., Collins, F. S., Cooper, C. C., Dennison, E. M., Erdos, M. R., Ferrannini, E., Fox, C. S., Graessler, J., Hao, K., Isomaa, B., Jameson, K. A., Kovacs, P., Kuusisto, J., Laakso, M., Ladenval, C., Mohlke, K. L., Morken, M. A., Narisu, N., Nathan, D. M., Pascoe, L., Payne, F., Petrie, J. R., Sayer, A. A., Schwarz, P. E., Scott, L. J., Stringham, H. M., Stumvoll, M., Swift, A. J., Syvanen, A., Tuomi, T., Tuomilehto, J., Tonjes, A., Valle, T. T., Williams, G. H., Lind, L., Barroso, I., Quertermous, T., Walker, M., Wareham, N. J., Meigs, J. B., McCarthy, M. I., Groop, L., Watanabe, R. M., Florez, J. C. AMER DIABETES ASSOC. 2010: 1266-1275

    Abstract

    OBJECTIVE Recent genome-wide association studies have revealed loci associated with glucose and insulin-related traits. We aimed to characterize 19 such loci using detailed measures of insulin processing, secretion, and sensitivity to help elucidate their role in regulation of glucose control, insulin secretion and/or action. RESEARCH DESIGN AND METHODS We investigated associations of loci identified by the Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC) with circulating proinsulin, measures of insulin secretion and sensitivity from oral glucose tolerance tests (OGTTs), euglycemic clamps, insulin suppression tests, or frequently sampled intravenous glucose tolerance tests in nondiabetic humans (n = 29,084). RESULTS The glucose-raising allele in MADD was associated with abnormal insulin processing (a dramatic effect on higher proinsulin levels, but no association with insulinogenic index) at extremely persuasive levels of statistical significance (P = 2.1 x 10(-71)). Defects in insulin processing and insulin secretion were seen in glucose-raising allele carriers at TCF7L2, SCL30A8, GIPR, and C2CD4B. Abnormalities in early insulin secretion were suggested in glucose-raising allele carriers at MTNR1B, GCK, FADS1, DGKB, and PROX1 (lower insulinogenic index; no association with proinsulin or insulin sensitivity). Two loci previously associated with fasting insulin (GCKR and IGF1) were associated with OGTT-derived insulin sensitivity indices in a consistent direction. CONCLUSIONS Genetic loci identified through their effect on hyperglycemia and/or hyperinsulinemia demonstrate considerable heterogeneity in associations with measures of insulin processing, secretion, and sensitivity. Our findings emphasize the importance of detailed physiological characterization of such loci for improved understanding of pathways associated with alterations in glucose homeostasis and eventually type 2 diabetes.

    View details for DOI 10.2337/DB09-1568

    View details for Web of Science ID 000277554700019

    View details for PubMedID 20185807

  • Fasting urine pH is independent of insulin sensitivity AMERICAN JOURNAL OF CLINICAL NUTRITION Workeneh, B., Abbasi, F., Reaven, G. 2010; 91 (3): 586-588

    Abstract

    It has recently been suggested that a low urine pH be added to the abnormalities linked to insulin resistance. This conclusion is based on the finding of a low urine pH in individuals with clinical syndromes associated with insulin resistance and not on studies in which a direct measure of insulin sensitivity was shown to be significantly related to differences in urine pH.To address this issue, we quantified insulin-mediated glucose uptake (IMGU) by using the insulin suppression test in 96 apparently healthy, nondiabetic individuals and defined its relation to fasting urine pH.Urine samples were collected and analyzed from a cohort of healthy subjects within a narrow body mass index range who were recruited to determine insulin sensitivity.There was an approximate 6-fold variation in values for IMGU in this population, with no relation to urine pH (r = 0.02). Furthermore, there was no relation between body mass index, as a surrogate estimate of insulin resistance, and urine pH (r = 0.06).On the basis of these findings, we question the view that a low urine pH be added to the abnormalities linked to insulin resistance in low-risk populations.

    View details for DOI 10.3945/ajcn.2009.28830

    View details for Web of Science ID 000274706500013

    View details for PubMedID 20032494

  • Metabolic impact of switching antipsychotic therapy to aripiprazole after weight gain - A pilot study JOURNAL OF CLINICAL PSYCHOPHARMACOLOGY Kim, S. H., Ivanova, O., Abbasi, F. A., Lamendola, C. A., Reaven, G. M., Glick, I. D. 2007; 27 (4): 365-368

    Abstract

    Switching antipsychotic regimen to agents with low weight gain potential has been suggested in patients who gain excessive weight on their antipsychotic therapy. In an open-label pilot study, we evaluated the metabolic and psychiatric efficacy of switching to aripiprazole in 15 (9 men, 6 women) outpatients with schizophrenia who had gained at least 10 kg on their previous antipsychotic regimen. Individuals had evaluation of glucose tolerance, insulin resistance (insulin suppression test), lipid concentrations, and psychiatric status before and after switching to aripiprazole for 4 months. A third of the individuals could not psychiatrically tolerate switching to aripiprazole. In the remaining individuals, psychiatric symptoms significantly improved with decline in Clinical Global Impression Scale (by 26%, P = 0.015) and Positive and Negative Syndrome Scale (by 22%, P = 0.023). Switching to aripiprazole did not alter weight or metabolic outcomes (fasting glucose, insulin resistance, and lipid concentrations) in the patients of whom 73% were insulin resistant and 47% had impaired or diabetic glucose tolerance at baseline. In conclusion, switching to aripiprazole alone does not ameliorate the highly prevalent metabolic abnormalities in the schizophrenia population who have gained weight on other second generation antipsychotic medications.

    View details for DOI 10.1097/JCP.0b013e3180a9076c

    View details for Web of Science ID 000248062400007

    View details for PubMedID 17632220

  • Fasting remnant lipoprotein cholesterol and triglyceride concentrations are elevated in nondiabetic, insulin-resistant, female volunteers JOURNAL OF CLINICAL ENDOCRINOLOGY & METABOLISM Abbasi, F., McLaughlin, T., Lamendola, C., Yeni-Komshian, H., Tanaka, A., Wang, T., Nakajima, K., Reaven, G. M. 1999; 84 (11): 3903-3906

    Abstract

    This study was initiated to test the hypothesis that plasma concentrations of remnant lipoproteins would be higher after an overnight fast in insulin-resistant compared to insulin-sensitive volunteers. Forty-three healthy nonobese women were studied, divided into insulin-resistant (n = 21) and insulin-sensitive (n = 22) groups on the basis of their steady state plasma glucose (SSPG) concentration at the end of a 180-min infusion of octreotide acetate, insulin, and glucose. Under these conditions, steady state plasma insulin concentrations are similar in all subjects (approximately 60 microU/mL), and the higher the SSPG concentrations, the more insulin resistant the individual. By selection, mean (+/-SEM) SSPG concentrations were significantly higher (P < 0.001) in the insulin-resistant group (210 +/- 7 vs. 78 +/- 3 mg/dL). In addition, the insulin-resistant group had higher triglycerides (198 +/- 27 vs. 101 +/- 12 mg/dL; P < 0.005) and lower high density lipoprotein cholesterol (48 +/- 4 vs. 60 +/- 4 mg/dL; P < 0.05) concentrations. Finally, insulin resistance was associated with higher remnant lipoprotein particle concentrations of cholesterol (7.2 +/- 0.8 vs. 4.4 +/- 0.3; P < 0.005) and triglycerides (22.2 +/- 3.4 vs. 8.5 +/- 1.0; P < 0.001). All of these differences were seen despite the fact that the two groups were similar in terms of age and body mass index. These results identify additional abnormalities in lipoprotein metabolism that may contribute to the increased risk of coronary heart disease seen in insulin-resistant, nondiabetic subjects (syndrome X).

    View details for Web of Science ID 000083555800007

    View details for PubMedID 10566626

  • Plasma homocysteine concentrations in healthy volunteers are not related to differences in insulin-mediated glucose disposal ATHEROSCLEROSIS Abbasi, F., Facchini, F., Humphreys, M. H., Reaven, G. R. 1999; 146 (1): 175-178

    Abstract

    This study was initiated to test the hypothesis that plasma homocysteine concentrations are increased in insulin resistant individuals. For this purpose, the relationship between insulin resistance, as assessed by the steady-state plasma glucose (SSPG) concentration during the insulin suppression test, and fasting plasma homocysteine concentration was defined in 55 healthy volunteers. The results indicated that homocysteine concentrations did not vary as a function of SSPG concentrations (r = 0.02, P = 0.88). Furthermore, mean (+/- S.E.M.) plasma homocysteine concentrations were similar (8.2+/-0.4 vs. 8.7+/-0.7 micromol/l) in individuals classified as being either insulin sensitive (SSPG <100 mg/dl) or insulin resistant (SSPG >180 mg/dl). On the other hand, SSPG concentration was significantly correlated with fasting plasma insulin (r = 0.58, P<0.001), triglycerides (r = 0.34, P<0.05), and HDL-cholesterol (r = -0.36, P = 0.04) concentrations. These data strongly suggest that the increased risk of atherosclerosis associated with increased plasma homocysteine concentrations is unrelated to insulin resistance and/or the metabolic abnormalities associated with it.

    View details for Web of Science ID 000082257900022

    View details for PubMedID 10487501

  • Mononuclear cell adherence to cultured endothelium is enhanced by hypertension and insulin resistance in healthy nondiabetic volunteers CIRCULATION Chen, N. G., Abbasi, F., Lamendola, C., McLaughlin, T., Cooke, J. P., Tsao, P. S., Reaven, G. M. 1999; 100 (9): 940-943

    Abstract

    This study was initiated to compare the adherence to cultured endothelial cells of mononuclear cells isolated from normotensive and hypertensive individuals.Mononuclear cell binding to endothelium was greater in patients with hypertension (32+/-1 versus 25+/-2; P<0.001) than in normal volunteers. There was a significant relationship (r=0.42, P<0. 01) between mononuclear cell binding and mean arterial pressure, independent of differences in age, sex, and body mass index. A significant relationship also existed between insulin resistance (estimated by the steady-state plasma glucose concentration during the insulin suppression test) and mononuclear cell binding in both the normotensive (r=0.86, P<0.001) and hypertensive (r=0.74, P<0. 001) groups. Furthermore, multiple regression analysis demonstrated an independent relationship (P<0.001) between mononuclear cell binding and both steady-state plasma glucose and hypertensive status.These results indicate that both hypertension and insulin resistance lead to changes in mononuclear cells that increase their adherence to cultured endothelial cells.

    View details for Web of Science ID 000082353000009

    View details for PubMedID 10468524

  • Differences in insulin resistance do not predict weight loss in response to hypocaloric diets in healthy obese women JOURNAL OF CLINICAL ENDOCRINOLOGY & METABOLISM McLaughlin, T., Abbasi, F., Carantoni, M., Schaaf, P., Reaven, G. 1999; 84 (2): 578-581

    Abstract

    The current study was initiated to determine whether insulin resistance and/or hyperinsulinemia affected the ability of obese individuals to lose weight in response to hypocaloric diets. Thirty-one obese, nondiabetic women, with values for body mass index ranging from 28.0-35.0 kg/m2, volunteered for this program. Resistance to insulin-mediated glucose disposal was assessed by determining their steady state plasma insulin and glucose concentration during the last 30 min of a 180-min infusion of somatostatin, insulin, and glucose. The total integrated insulin response to breakfast and lunch was also determined. After the baseline measurements, volunteers were placed on a hypocaloric diet calculated to lead to a minimum weekly loss of 1% of ideal body weight. Individuals who met the criteria after 30 days of dieting were defined as weight loss successes (n = 20) and continued on the diet for another 30 days. Individuals not meeting the criteria were designated as weight loss failures (n = 12) and were discharged from the study. There was a mean (+/-SEM) weight loss at 60 days of 9.2 +/- 0.4 kg in the 20 individuals defined as weight loss successes, but there was no correlation between weight loss and either steady state plasma glucose or the total integrated insulin response (r < 0.1; P > 0.83). Furthermore, using the same criteria to define insulin sensitivity and insulin resistance as those for therapeutic successes, the therapeutic failures comprised six insulin-sensitive and five insulin-resistant subjects. In summary, insulin-mediated glucose disposal varied widely in nondiabetic, obese women, and there was no relationship between baseline insulin resistance or total integrated insulin response and weight loss. It is concluded that the ability to lose weight on a calorie-restricted diet over a short time period does not vary in obese, healthy women as a function of insulin resistance or hyperinsulinemia.

    View details for Web of Science ID 000078464000031

    View details for PubMedID 10022419

  • Further evidence for a central role of adipose tissue in the antihyperglycemic effect of metformin DIABETES CARE Abbasi, F., Carantoni, M., CHEN, Y. D., Reaven, G. M. 1998; 21 (8): 1301-1305

    Abstract

    To evaluate further the relative roles played by liver and adipose tissue in the therapeutic response to metformin in patients with type 2 diabetes.A total of 11 patients with diet-treated type 2 diabetes were given metformin for approximately 3 months. Measurements were made before and after treatment of 1) fasting and postprandial plasma glucose, insulin, and free fatty acid (FFA) concentrations; 2) glucose appearance (Ra) and disappearance (Rd) rates measured overnight with 3-[3H]glucose; and 3) plasma FFA concentrations during a 195-min infusion period at relatively low insulin (approximately 12-24 microU/ml) concentrations.Mean +/- SEM fasting plasma glucose concentration was significantly lower (175 +/- 11 vs. 224 +/- 15 mg/dl; P < 0.01) after treatment with metformin. Mean +/- SEM insulin concentrations measured from 8:00 A.M. to 5:00 P.M. did not change with treatment. However, both glucose and FFA concentrations were significantly lower (P < 0.01) when measured over the same time period, and the decreases in plasma FFA and glucose concentration were highly correlated (r = 0.81; P = 0.03). Overnight glucose turnover studies indicated that neither Ra (hepatic glucose production [HGP]) nor Rd changed significantly with treatment in association with metformin treatment. Since plasma glucose concentration was much lower after metformin treatment, the overnight glucose metabolic clearance rate (MCR) was significantly lower (P < 0.01). Finally, the ability of insulin to inhibit isoproterenol-stimulated increases in plasma FFA concentration was enhanced in metformin-treated patients (P < 0.05).Metformin treatment was associated with significantly lower fasting plasma glucose concentrations and lower day-long plasma glucose and FFA concentrations. Although overnight HGP was unchanged after treatment with metformin, the overnight glucose MCR was significantly increased, and the antilipolytic activity of insulin was also enhanced. Given these findings, it is suggested that at least part of the antihyperglycemic effect of metformin is due to a decrease in release of FFA from adipose tissue, leading to lower circulating FFA concentrations and an increase in glucose uptake.

    View details for Web of Science ID 000075177900017

    View details for PubMedID 9702437

  • Relationship between insulin resistance and partially oxidized LDL particles in healthy, nondiabetic volunteers ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY Carantoni, M., Abbasi, F., Warmerdam, F., Klebanov, M., Wang, P. W., CHEN, Y. D., Azhar, S., Reaven, G. M. 1998; 18 (5): 762-767

    Abstract

    This study was performed in 36 healthy volunteers to define the relationship between plasma concentrations of partially oxidized low density lipoprotein (poxLDL), plasma glucose and insulin responses to oral glucose, and steady-state plasma glucose (SSPG) concentrations after a 180-minute infusion of somatostatin, insulin, and glucose. The concentration of poxLDL was estimated by determining the amount of conjugated dienes formed during in vitro LDL oxidation in the presence or absence of alanine. Under these conditions, the greater the in vitro antioxidant effect of alanine, the lower the amount of poxLDL that was present in plasma. The results demonstrated that plasma poxLDL concentration was significantly correlated with plasma glucose (r=.53, P<.001) and insulin (r=.43, P<.01) responses, SSPG concentrations (r=.53, P<.001), and plasma triglyceride (r=.42, P<.01) and HDL cholesterol (r=-.50, P<.002) concentrations. Furthermore, these relationships persisted when the data were corrected for differences in age, sex, body mass index, and the ratio of waist to hip girth. Of note, there was no correlation between poxLDL and LDL cholesterol concentration. When SSPG was entered along with age, sex, body mass index, and waist-to-hip ratio in a multiple regression model, SSPG alone was a significant prediction of poxLDL (r-=.37, P<.02). The addition of plasma glucose and insulin responses and triglyceride and HDL cholesterol concentrations increased the r2 to only .47. These results show that the amount of poxLDL in plasma is significantly correlated with insulin resistance (ie, SSPG) and its metabolic consequences.

    View details for Web of Science ID 000073770100012

    View details for PubMedID 9598835

  • Plasma leptin concentrations do not appear to decrease insulin-mediated glucose disposal or glucose-stimulated insulin secretion in women with normal glucose tolerance DIABETES Carantoni, M., Abbasi, F., Azhar, S., CHEN, Y. D., Klebanov, M., Wang, P. W., Warmerdam, F., Reaven, G. M. 1998; 47 (2): 244-247

    Abstract

    The aim of this study was to test the hypothesis that plasma leptin concentrations contributed to the pathophysiology of NIDDM by decreasing both insulin-mediated glucose disposal and glucose-stimulated insulin secretion. The study was performed in 60 women with normal oral glucose tolerance. Differences in insulin-mediated glucose disposal were determined by comparing the steady-state plasma glucose (SSPG) concentrations attained at the end of a 180-min constant infusion of somatostatin, glucose, and insulin, while comparisons of glucose-stimulated insulin secretion were based on the incremental increase in insulin concentration 30 min after an oral glucose challenge (deltaIns) as compared with the fasting value. The results showed that the higher the fasting plasma leptin concentration, the greater the degree of insulin resistance (r = 0.47, P < 0.01). Furthermore, multiple regression analysis indicated that the relationship between leptin and SSPG was independent of age and degree of obesity as estimated by BMI. However, since the total integrated plasma insulin response was highly correlated with both SSPG (r = 0.80, P < 0.001) and leptin (r = 0.55, P < 0.01), multiple regression analysis was repeated, adding total insulin response to the model. When this was done, the significant relationship between leptin and SSPG disappeared, whereas both BMI (P < 0.03) and insulin response (P < 0.001) were correlated with SSPG. A significant relationship between leptin and deltaIns was seen, but it was a positive one (r = 0.31, P < 0.02), not a negative one as would be expected if circulating levels of leptin inhibited glucose-stimulated insulin secretion. Furthermore, multiple regression analysis could only confirm an independent relationship between deltaIns and SSPG, but not between deltaIns and leptin. The results of these studies do not support the view that circulating leptin has a primary effect on either insulin action or secretion in normal female volunteers. It seems more likely that chronic hyperinsulinemia in insulin-resistant individuals acts to increase adipose tissue leptin synthesis and secretion, leading to higher ambient leptin concentrations.

    View details for Web of Science ID 000071689400014

    View details for PubMedID 9519720

  • Results of a placebo-controlled study of the metabolic effects of the addition of metaformin to sulfonylurea-treated patients - Evidence for a central role of adipose tissue DIABETES CARE Abbasi, F., Kamath, V., Rizvi, A. A., Carantoni, M., CHEN, Y. D., Reaven, G. M. 1997; 20 (12): 1863-1869

    Abstract

    To define the metabolic effects of metformin in the treatment of NIDDM and to evaluate potential mechanisms for its ability to improve glycemic control.Sulfonylurea-treated patients, with inadequate glycemic control, were treated with metformin in either a placebo-controlled or open fashion. Measurements were made of 1) fasting and postprandial plasma glucose, insulin, and free fatty acid (FFA) concentrations; 2) glucose appearance and disappearance rates measured overnight with 3-[3H]glucose; and 3) plasma FFA concentrations during a 45-min infusion period at relatively low (approximately 60 pmol/l) insulin concentrations.Mean +/- SE hourly plasma glucose, insulin, and FFA concentrations were similar before and after treatment in the placebo group. In contrast, mean hourly plasma glucose concentrations were significantly lower (P < 0.005) after metformin treatment in both the placebo-controlled and open-label groups (-3.9 +/- 1.0 and -4.4 +/- 0.8 mmol/l, respectively). Similarly, day-long hourly FFA levels were lower (P < 0.005) following metformin in the placebo-controlled and open-label groups (-87 +/- 35 and -136 +/- 31 mumol/l, respectively). Plasma insulin concentrations did not change with treatment in any group. Overnight glucose turnover studies indicated that neither the rate of glucose appearance (hepatic glucose production) or glucose disappearance changed significantly with treatment in the placebo or metformin groups. Because plasma glucose concentration was much lower after metformin treatment, overnight glucose metabolic clearance rate was significantly (P < 0.001) lower in this group. Finally, plasma FFA concentrations in response to a low-dosage insulin infusion (5 mU.m-2.min-1) were significantly lower after metformin as compared with the placebo-treated group (P < 0.001).Metformin treatment was associated with significantly lower day-long plasma glucose and FFA concentrations. Although overnight hepatic glucose production was unchanged following treatment with metformin, the overnight glucose metabolic clearance rate significantly increased. Given these findings, it is suggested that at least part of the antihyperglycemic effect of metformin is due to an increase in glucose uptake, secondary to a decrease in release of FFA from adipose tissue, and lower circulating FFA concentrations.

    View details for Web of Science ID A1997YH35900012

    View details for PubMedID 9405908

  • Insulin resistance does not change the ratio of proinsulin to insulin in normal volunteers JOURNAL OF CLINICAL ENDOCRINOLOGY & METABOLISM Wang, P. W., Abbasi, F., Carantoni, M., CHEN, Y. D., Azhar, S., Reaven, G. M. 1997; 82 (10): 3221-3224

    Abstract

    Plasma glucose, insulin, and proinsulin concentrations were measured before and after an oral glucose challenge in 57 nondiabetic individuals. In addition, insulin-mediated glucose disposal was estimated by determining the steady state plasma glucose (SSPG) concentration after a 180-min iv infusion of somatostatin, insulin, and glucose. The plasma glucose concentration after oral glucose administration was used to divide the population into those with normal (n = 36) or impaired glucose tolerance (IGT; n = 21), and the 36 normal glucose-tolerant individuals were further subdivided into an insulin-sensitive (SSPG, < 9.0 mmol/L; n = 15) and an insulin-resistant (SSPG, > 10 mmol/L; n = 21) group. Fasting and postglucose load insulin concentrations were similar in the normal glucose-tolerant insulin-resistant and IGT groups, but were significantly higher (P < 0.02- < 0.001) than those in normal glucose-tolerant insulin-sensitive individuals. Fasting proinsulin concentrations were also higher (P < 0.002) in the normal glucose-tolerant insulin-resistant (15.1 +/- 1.5 pmol/L) and IGT (15.8 +/- 1.8 pmol/L) groups compared to those in normal glucose-tolerant insulin-sensitive volunteers (9.3 +/- 1.2 pmol/ L). However, the ratio of fasting proinsulin to insulin was identical in all three groups (0.12). When the three groups were combined, significant relationships (P < 0.001) existed between SSPG (degree of insulin resistance) and both fasting proinsulin (r = 0.59) and insulin (r = 0.66) concentrations, but not with the ratio of proinsulin to insulin (r = 0.03). These results demonstrate that fasting proinsulin and insulin concentrations are increased in insulin-resistant, nondiabetic subjects, and the more insulin resistant, the greater the increase. In contrast, the ratio of proinsulin to insulin did not vary as a function of insulin resistance. Thus, neither insulin resistance nor the need to secrete more insulin to maintain glucose tolerance necessarily leads to abnormal insulin processing by the beta-cell.

    View details for Web of Science ID A1997YA00200008

    View details for PubMedID 9329342

  • Adherence of mononuclear cells to endothelium in vitro is increased in patients with NIDDM DIABETES CARE Carantoni, M., Abbasi, F., Chu, L., CHEN, Y. D., Reaven, G. M., Tsao, P. S., Varasteh, B., Cooke, J. P. 1997; 20 (9): 1462-1465

    Abstract

    To compare the binding to cultured endothelial cells of mononuclear cells isolated from healthy volunteers and patients with NIDDM.Mononuclear cells were isolated from healthy volunteers (n = 11) and patients with NIDDM (n = 14) and incubated with ECV 304 cells, a human umbilical endothelial cell-derived transformed cell line. Following a period of incubation, the adherence of mononuclear cells to endothelial cells was determined.Adherence of mononuclear cells from patients with NIDDM was significantly greater (P < 0.05) than that of cells isolated from the healthy volunteers, and this difference persisted when adjusted for age, sex, and degree of obesity. Mononuclear cell binding to ECV 304 cells correlated significantly with fasting plasma glucose (r = 0.52, P < 0.01), insulin (r = 0.51, P < 0.01), triglyceride (r = 0.54, P < 0.01), and VLDL (r = 0.54, P < 0.01) and HDL cholesterol (r = -0.45, P < 0.05) levels, but not with either total or LDL cholesterol levels or blood pressure.Since the adherence of mononuclear cells to the endothelium represents the earliest step in atherogenesis, the observation that mononuclear cells from patients with NIDDM bind more avidly to cultured endothelial cells may help explain why accelerated atherosclerosis occurs in patients with NIDDM. The metabolic abnormality, or abnormalities, present in patients with NIDDM that is responsible for the enhanced adhesiveness of mononuclear cells requires further examination.

    View details for Web of Science ID A1997XT09100023

    View details for PubMedID 9283798