Insulin Sensitivity Differs among Ethnic Groups with a Compensatory Response in Beta Cell Function

Objective: There is a drastic difference in the prevalence of type 2 diabetes among ethnic groups. We examined the role of beta cell function and insulin sensitivity in this disparity among four ethnic groups. Research Design and Methods: Beta cell function and insulin sensitivity were assessed in 77 healthy glucose tolerant subjects using a hyperglycemic clamp. There were 18 Asian-, 9 African-, 34 Caucasian-, and 16 Mexican-Americans. Results: There was a wide range of variation in clinical features of the studied subjects. Insulin sensitivity index and the second phase insulin response differed among the four groups (P=0.0023 and P=0.0082, respectively), while the first phase insulin response was marginally different (P=0.1090). A stepwise regression analysis revealed that ethnicity was an independent determinant for insulin sensitivity index (P=0. 0014), after adjusting for gender, age, diastolic blood pressure, waist-hip ratio and body mass index. Also, compensatory response of beta cell function was observed among the ethnic groups. Conclusion: In the present study, we observed a drastic difference in insulin sensitivity among the different ethnic groups and that their beta cell function compensates for the prevailing insulin sensitivity. The difference in the prevalence of abnormal glucose tolerance in different ethnic groups could be a result of differences in insulin sensitivity