Insulin Response in Relation to Insulin Sensitivity An appropriate -cell response in black South African women

OBJECTIVE — The purpose of this study was to characterize differences in the acute insulin response to glucose (AIRg) relative to insulin sensitivity (SI) in black and white premenopausal normoglycemic South African women matched for body fatness. RESEARCH DESIGN ANDMETHODS — Cross-sectional analysis including 57 black and white South African women matched for BMI, SI, AIRg, and the disposition index (AIRg SI) were performed using a frequently sampled intravenous glucose tolerance test with minimal model analysis, and similar measures were analyzed using an oral glucose tolerance test (OGTT). Body composition was assessed by dual-energy X-ray absorptiometry and computed tomography. RESULTS — SI was significantly lower (4.4 0.8 vs. 9.4 0.8 and 2.9 0.8 vs. 6.0 0. 8 105 min1/[pmol/l], P 0.001) and AIRg was significantly higher (1,028 255 vs. 352 246 and 1,968 229 vs. 469 246 pmol/l, P 0.001), despite similar body fatness (30.9 1.4 vs. 29.7 1.3 and 46.8 1.2 vs. 44.4 1.3%) in the normal-weight and obese black women compared with their white counterparts, respectively. Disposition index, a marker of -cell function, was not different between ethnic groups (3,811 538 vs. 2,966 518 and 3,64