Does aging intensify the insulin resistance of human obesity?
Relative insulin sensitivity in aging and obesity was studied during 6-h euglycemic-hyperinsulinemic clamp procedures in seven nonobese weight-matched premenopausal (Pre-M) and postmenopausal (Post-M) women and in nine weight-matched obese Pre-M and Post-M subjects. Peripheral glucose disappearance rates (Rd) and endogenous glucose production rates (EGPR) were measured during baseline (0-2 h) and at insulin delivery rates of 10 (2-4 h) and 40 mU/m2.min (4-6 h). Baseline Rd and EGPR were comparable in the four groups. In Pre-M nonobese women, Rd rose 1.6- and 4-fold above baseline, respectively, at 2-4 and 4-6 h. In all other groups Rd did not change at the lower insulin delivery rate and rose only 2-fold above baseline at the higher delivery rate. EGPR was suppressed 61% and 100% at the two insulin infusion rates, respectively, in Pre-M nonobese subjects. Similar normal suppression was observed in Post-M nonobese individuals. However, in both obese groups, EGPR suppression was comparab
