Postprandial Insulin Response and Clearance Among Black and White Women: The Federal Women's Study.

ABSTRACT

Context Postprandial hyperinsulinemia might be an important cardiometabolic risk determinant in black compared with white women. However, the contributions of insulin clearance and ß-cell function to racial differences in postprandial insulin response are unknown. Objective: To compare, by race and menopause, early insulin response to oral and intravenous glucose and to measure postprandial intact glucagon-like peptide 1 (GLP-1) concentrations, insulin clearance, and ß-cell function. Design and Participants: 119 federally employed women without diabetes [87 premenopausal (52 black, 35 white) and 32 postmenopausal (19 black, 13 white)] underwent an oral glucose tolerance test, insulin-modified frequently sampled intravenous glucose test (IM-FSIGT), and mixed meal tolerance test (MMTT). Outcome Measures: Early insulin response was measured as follows (i) insulinogenic index (oral glucose tolerance test); (ii) acute insulin response to glucose (IM-FSIGT); and (iii) ratio of incremental insulin/glucose area under the curve in the first 30 minutes of the MMTT. Insulin clearance was assessed during the IM-FSIGT and MMTT. During the MMTT, intact GLP-1 was measured and ß-cell function assessed using the insulin secretion rate and ß-cell responsivity indexes. Results: Black pre-menopausal and postmenopausal women had a greater insulin response and lower insulin clearance and greater dynamic ß-cell responsivity (P ≤ 0.05 for all). No differences were found in the total insulin secretion rates or intact GLP-1 concentrations. Conclusions: Greater postprandial hyperinsulinemia in black pre-menopausal and postmenopausal women was associated with lower hepatic insulin clearance and heightened ß-cell capacity to rapid changes in glucose, but not to higher insulin secretion. The relationship of increased ß-cell secretory capacity, reduced insulin clearance, and ambient hyperinsulinemia to the development of cardiometabolic disease requires further investigation.