Effect of Variations in Basal Plasma Glucose Concentration on Glucose Utilization (M) and Metabolic Clearance (MCR) Rates During Insulin Clamp Studies in Patients with Non-insulin-dependent Diabetes Mellitus

Two insulin clamp studies were performed at different steady-state plasma glucose concentrations in 13 patients with non-insulin-dependent diabetes mellitus (NIDDM). Steady-state plasma insulin concentrations were comparable, with mean ± SEM levels of 94 ± 3 and 95 ± 4 μU/ml being achieved during the two studies. Glucose utilization rate (M) varied directly with plasma glucose concentration in each subject. Thus, the mean ± SEM value of M was 4.92 ± 0.73 mg/kg/min when patients were studied at a mean ± SEM plasma glucose concentration of 226 ± 15 mg/dl, and M was 2.71 mg/kg/min when the same subjects were studied at a glucose concentration of 118 ± 6 mg/dl. In contrast, the values for glucose metabolic clearance rate (MCR), which were 2.35 ± 0.50 and 2.49 ± 0.47 ml/kg/min, respectively, during the two studies, did not vary significantly with plasma glucose concentration. These data indicate that the glucose metabolic clearance rate (MCR), but not glucose utilization rate (M), can be used to compare in vivo insulin action when insulin clamp studies are performed in subjects with different basal plasma glucose concentrations.