Racial differences in the correlation between gonadal androgens and serum insulin levels

OBJECTIVE - We preciously demonstrated a direct correlation between serum i nsulin levels and gonadal androgens (testosterone and androstenedione) in a group of obese hyperandrogenic predominantly black women. Subsequent work by others in predominantly white women showed conflicting results. To, exam ine these. potentially important racial differences further, 14 premenopaus al females from each ethnic group, of similar age, BMI, and waist-to-hip ra tio, were studied. RESEARCH DESIGN AND METHODS - We measured baseline gonadal androgens, dehyd roepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS). and leuti nizing hormone (LH)/follicle-stimulating hormone ratio. Serum glucose. insu lin, and C-peptide were measured at baseline and during a 2-h oral glucose tolerance test (area under the curve [AUC]). Insulin sensitivity was measur ed by glucose decrement during the first 15 min of an intravenous insulin t olerance test. RESULTS - Simple correlation analysis revealed a significant direct correla tion in blacks (but not whites) between gonadal androgens and AUC for gluco se, insulin, and C-peptide. Race-by-covariate interaction models reinforced the simple correlation finding. Cholesterol level was also correlated to a ll androgens in blacks, but not in whites. We also found that whites had hi gher serum triglycerides and greater AUC glucose than blacks. CONCLUSIONS - We conclude that there is a significant direct correlation be tween gonadal androgens and stimulated glucose, insulin, and C-peptide in b lacks but not in whites. Thus, the previously reported direct correlation b etween gonadal hyperandrogenism and hyperinsulinemia may be a race-dependen t phenomenon, hitherto an unreported observation. The implications of these findings are discussed.