Euglycemic Glucose Clamp

Studies were done to determine whether the minimal model approach and the glucose clamp measure equivalent indices of insulin action. Euglycemic glucose clamps (glucose, G: 85 mg/dl) were performed at two rates of insulin (I) infusion (15 and 40 mU/min per in2) in 10 subjects (body mass index, BMI, from 21 to 41 kg/m2). Insulin sensitivity index (SI) from clamps varied from 0.15 to 3.15 (mean: 1.87±0.36 X 10-2 dl/Imin per m2l per XU/ml), and declined linearly with increasing adiposity (versus BMI: r = -0.97; P < 0.00t). SI from modeling the modified frequently sampled intravenous tolerance test varied from 0.66 to 7.34 X 10-4 min-' per gU/ml, and was strongly correlated with SIp(cFOip) (r = 0.89; P < 0.001). SI and SIP(clp) were similar (0.046±0.008 vs. 0.037±0.007 dl/min per tU/mt, P > 035); the relation had a slope not different from unity (1.05 P > 0.70) and passed through the origin (P > 0.40). However, on a paired basis, SI exceeded SIP(cl,,amp) slightly, due to inhibition of hepatic glucose output during the FSIGT, not included in Smpowi). These methods are equivalent for assessment of overall insulin sensitivity in normal and insulin-resistant nondiabetic subjects.