Insulin sensitivity assessment in uncomplicated obese women: comparison of indices from fasting and oral glucose load with euglycemic hyperinsulinemic clamp

Abstract

Obesity is associated with a great variability to insulin sensitivity degree. Several formulae developed from measurements in the fasting state and during the oral glucose tolerance test (OGTT) have been proposed to assess insulin sensitivity. In this work we sought to compare the published insulin sensitivity indices with the metabolized glucose index obtained by hyperinsulinemic euglycemic clamp in uncomplicated obese subjects. Uncomplicated obesity provides a good model in order to study insulin sensitivity per se. In this protocol, 65 obese women affected by uncomplicated obesity (without impaired glucose tolerance, diabetes, hypertension and dyslipidemia) underwent 2 h OGTT and euglycemic hyperinsulinemic clamp. Common formulae obtained in the fasting state and from a 2h OGTT were calculated. Simple linear regression analysis showed that ISI (r=0.592, p=0.01), 2 h OGIS (r=0.576, p=0.02), MCRest (r=0.507, p=0.02), 120 insulin (r=-0.494, p=0.03) and fasting insulin (r=-0.382, p =0.02) are significantly correlated to the M index obtained from the hyperinsulinemic euglycemic clamp. The Bland-Altman plot confirmed the good agreement between indices from OGTT and the clamp. OGTT-derived indices provide a good assessment of insulin sensitivity in obesity. OGTT could easily be applied in a large number of obese patients in order to obtain information on both glucose tolerance and insulin sensitivity.