Abstract
Only a few studies have investigated the range of fasting plasma glucose (FPG) in which insulin resistance as measured by homeostasis model assessment (HOMA) and by euglycemic clamping might highly correlate. To determine this range, we attempted to determine whether the correlation coefficient between the HOMA-estimate of insulin resistance (HOMA-IR) and the reciprocal of glucose infusion rate (GIR) during euglycemic clamping changes with an increase in FPG in patients with obese and non-obese type 2 diabetes mellitus (DM). We measured HOMA-IR (fasting glucose [mg/dl]×fasting insulin [μU/m/]/405) and GIR (mg/kg/min) during 90-minute euglycemic (80mg/dl) and hyperinsulinemic (63±18μU/ml) clamping studies in 42 patients with type 2 DM. Patients were 27 men and 15 women, 57.3±12 years of age, and either obese (body mass index [BMI]≥25kg/m2, 17 patients) or non-obese (BMI≤25kg/m2, 25 patients). Their average FPG was 140±38mg/dl. In 15 patients (FPG<170mg/dl, BMI≥25kg/m2), HOMA-IR and 1/GIR were highly correlated (r=0.82, p<0.01). In this range of FPG, fasting insulin was significantly correlated with both 1/GIR and HOMA-IR, however, BMI, TG and TCho were not correlated with either 1/GIR or HOMA-IR. Age, sex and oral hypoglycemic agent also had no association with 1/GIR and HOMA-IR.
In conclusion, these results suggest that HOMA-IR is a useful index for determining insulin resistance at the FPG range of 80-170 mg/dl in patients with obese type 2 DM.
