Evidence for physiological coupling of insulin-mediated glucose metabolismand limb blood flow

We hypothesized that the vasodilation observed during insulin stimulation i s closely coupled to the rate of glucose metabolism. Lean (L, n = 13), obes e nondiabetic (OB, n = 13), and obese type 2 diabetic subjects (Type 2 DM, n = 16) were studied. Leg blood flow (LBF) was examined under conditions of euglycemic hyperinsulinemia (EH) and hyperglycemic hyperinsulinemia (HH), which produced a steady-state whole body glucose disposal rate (GDR) of sim ilar to2,000 mu mol.m(-2).min(-1). At this GDR, under both conditions, subj ects across the range of insulin sensitivity exhibited equivalent LBF (l/mi n EH: L, 0.42 +/- 0.03; OB, 0.43 +/- 0.03; Type 2 DM, 0.38 +/- 0.07; P = 0. 72 by ANOVA. HH: L, 0.44 +/- 0.04; OB, 0.39 +/- 0.05; Type 2 DM, 0.41 +/- 0 .04; P = 0.71). The continuous relationship between LBF and GDR did not dif fer across subject groups [slope x 10(-5) l/(mu mol.m(-2).min(-1))by ANOVA. EH: L, 8.6; OB, 9.2; Type 2 DM, 7.9; P = 0.91. HH: L, 4.2; OB, 2.5; Type 2 DM, 4.1; P = 0.77], although this relationship did differ between the EH a nd HH conditions (P = 0.001). These findings support a physiological coupli ng of LBF and insulin-mediated glucose metabolism. The mechanism( s) linkin g substrate delivery and metabolism appears to be intact in insulin-resista nt states.