A Cross-Sectional Characterization of Insulin Resistance by Phenotype and Insulin Clamp in East Asian Americans with Type 1 and Type 2 Diabetes

Classic features of type 1 and type 2 diabetes may not apply in Asian Americans, due to shared absence of common HLA DR-DQ genotype, low prevalence of positive anti-islet antibodies and low BMI in both types of diabetes. Our objective was to characterize diabetic phenotypes in Asian Americans by clamp and clinical features.This was a cross-sectional study conducted in a referral center. Thirty East young Asian American adult volunteers (27.6±5.5 years) with type 1, type 2 diabetes or controls underwent hyperinsulinemic euglycemic clamp to assess insulin resistance and DEXA to assess adiposity.Gender, BMI, waist/hip ratio, leptin, LDL, anti-GAD, anti-IA2 antibodies and C-reactive protein were similar among three groups. Serum C-peptide, adiponectin, free fatty acid, HDL concentrations and truncal fat by DEXA, were different between diabetic groups. Glucose disposal rate by clamp was lowest in type 2 diabetes, followed by type 1 diabetes and controls (5.43±2.70, 7.62±2.59, 8.61±2.37 mg/min/kg, respectively, p = 0.001). Free fatty acid concentration universally plummeted during steady state of the clamp procedure regardless of diabetes types in all three groups. Adipocyte fatty acid binding protein in the entire cohort (r = -0.625, p = 0.04) and controls (r = -0.869, p = 0.046) correlated best with insulin resistance, independent of BMI.Type 2 diabetes in Asian Americans was associated with insulin resistance despite having low BMI as type 1 diabetes, suggesting a potential role for targeting insulin resistance apart from weight loss. Adipocyte fatty acid binding protein, strongly associated with insulin resistance, independent of adiposity in the young Asian American population, may potentially serve as a biomarker to identify at-risk individuals. Larger studies are needed to confirm this finding

Gross and Adjusted Correlations with GDR.

<p>Data are presented as Pearson correlation coefficient (R), and corresponding p value. Variables presented: BMI, C-Reactive Protein (CRP), Adipocyte Fatty Acid-Binding Protein (A-FABP), Retinol Binding Protein-4 (RBP-4), Total Body Fat (TBF%) by DEXA, and Truncal Fat percentage (TF%). Type 1 diabetes group (Type 1), Type 2 diabetes group (Type 2). Adjusted correlations with GDR by age, gender and BMI.</p

Baseline characteristics, separated by group.

<p>Data are means ± SD or n (%). ANOVA performed between all 3 groups: Type 1 Diabetes, Type 2 Diabetes, and Controls.</p><p>*Auto-antibody positivity to islet cell antigens was determined by serum concentration>0.1 nU/ml for GAD & IA2, expressed as number of individuals (percent positive).</p>‡<p>Chi-Square tests were performed in these categories.</p

Relationship between glucose infusion rate (GDR) and various biomarkers for insulin resistance.

<p>Relationship between GDR and Adiponectin, Free fatty acid (FFA), Waist circumference, A-FABP, C-reactive protein (CRP), Total Body Fat (TBF) by DEXA, BMI, and Retinol Binding Protein-4 (RBP-4). Circles = Type 1 group; Squares = Type 2 diabetes group; Triangles = Control group.</p