Inverse relationship of metabolic clearance rate of insulin to body mass index

Twenty-five human subjects, whose body mass indices (BMI) ranged from 18.0 to 34.1 kg/m2, underwent euglycemic clamps at both low (1.5 mU/kg/min) and high (10 mU/kg/min) insulin infusion rates. Mean C-peptide concentrations were less than or equal to 0.5 ng/mL at the end of each two-hour period. The metabolic clearance rates (MCR) of insulin (mL/kg/min) were significantly (P less than .001) inversely correlated with BMI at both the low (r = -.65) and high (r = -.71) insulin infusion rates. The negative inverse correlations with BMI remained significant at both the low (r = -.42, P less than .05) and high (r = -.61, P less than .005) insulin infusion rates if the MCR were expressed as mL/m2/min. There were no significantly correlations (r less than .21) between the MCR at either rates of insulin infusion and age or tracer insulin binding to monocytes. Decreased MCR of insulin may contribute to the hyperinsulinemia seen in obese subjects.