Insulin Response in a Triethnic Population: Effects of Sex, Ethnic Origin, and Body Fat: The Miami Community Health Study

OBJECTIVE To assess sex and ethnic differences in hyperinsulinemia/insulin resistance and to examine the impact of percent body fat on such differences. RESEARCH DESIGN AND METHODS A cross-sectional epidemiological study was performed in a normoglycemic population of African-Americans ( n = 159), Cuban Americans ( n = 128), and non-Hispanic whites ( n = 207) who resided in Dade County, Florida, from 1990 to 1995. The insulin area under the curve (AUC) in response to a standard 75-g oral glucose tolerance test (OGTT) was used as an indicator of hyperinsulinemia/insulin resistance. Analysis of covariance was performed to compare sex and ethnic differences in the insulin AUC. Multiple linear regression was used to evaluate the independent correlates of the insulin AUC. RESULTS After covariate adjustment for percent body fat, men displayed a significantly higher insulin AUC than did women ( P P = 0.01). Alcohol consumption was inversely related to AUC ( P = 0.04). CONCLUSIONS Despite the greater percentage of body fat in women, the insulin AUC was similar in women and men. After adjustment for the sex difference in percent body fat, women displayed a lower insulin AUC than did men, indicating enhanced insulin sensitivity. These differences by sex and ethnicity in insulin resistance are consistent with established differences in heart-disease risk (i.e., higher in men and African-Americans) and suggest that hyperinsulinemia/insulin resistance may partly underlie such differences.