Relationship between generalized and upper body obesity to insulin resistance in Asian Indian men

It has been proposed that excessive insulin resistance in Asian Indians liv ing in urban areas or migrated to western countries is responsible for the higher incidence of type 2 diabetes and coronary heart disease observed in this population. To evaluate whether Asian Indians are more insulin resista nt than Caucasians and to define the role of generalized and truncal adipos ity, we performed hydrodensitometry , skinfold measurements, and euglycemic -hyperinsulinemic clamps in 21 healthy Asian Indian men and 23 Caucasian me n of similar age and body fat content. The glucose disposal rate (Bd) was s ignificantly lower in the Asian Indians than in the Caucasians (3.7 +/- 1.3 vs. 5.3 +/- 2.0 mg/min.kg lean body mass, respectively; P = 0.003). Despit e similar total body fat content, Asian Indians had higher truncal adiposit y than Caucasians (sum of truncal skinfolds, 117 +/- 37 and 92.4 +/- 38 mm, respectively). In both Asian Indians and Caucasians, the insulin sensitivi ty index (Rd/plasma insulin concentrations) was inversely correlated with b oth total body fat (r = -0.49; P < 0.03 and r = -0.67; P < 0.001, respectiv ely) and sum of truncal skinfold thickness (r = -0.55; P < 0.001 and r = -0 .61; P < 0.002, respectively). After adjustment for total body fat and trun cal skinfold thickness, Asian Indians still had a significantly lower gluco se disposal rate (P = 0.04). These results show that Asian Indian men are m ore insulin resistant than Caucasian men independently of generalized or tr uncal adiposity. The excessive insulin resistance in Asian Indians is proba bly a primary metabolic defect and may account for the excessive morbidity and mortality from diabetes and coronary heart disease in this population.