Early impairment of β-cell function and insulin sensitivity characterizes normotolerant Caucasian women with previous gestational diabetes

Background and aims: Women with previous gestational diabetes (pGDM) are at high risk of developing type 2 diabetes mellitus. The aim of this study was to evaluate insulin action and insulin secretion in women with pGDM. Methods and results: One hundred and fifty-three pGDM women and 45 with normal glucose tolerance during pregnancy (controls) were studied 1-3 years after delivery. Insulin sensitivity (ISI) and beta-cell secretory capacity (beta-index) were derived from 75-g OGTT. Disposition Index was calculated as the product of P-index and ISI. One hundred and twenty-two pGDM were normotolerant (NGT) and 31 had impaired glucose regulation (IGR) i.e. impaired glucose tolerance and/or impaired fasting glucose. NGT-pGDM, as compared to controls, had significant impairment in insulin action (ISI: 5.46 +/- 2.81 vs. 7.38 +/- 3.68, P < 0.01) and insulin secretion (P-index: 4.68 +/- 1.01 vs. 5.24 +/- 0.82 pmol/min/m(2); P < 0.01). A further impairment was apparent in IGR-pGDM for beta-index (4.16 +/- 1.09; P < 0.05). The disposition index was reduced in NGT-pGDM as compared to controls (33.9%) and further reduced in IGR-pGDM (28.6%, vs. NGT-pGDM; ANOVA P < 0.001). In women of normal weight, ISI and P-index were significantly (P < 0.01) impaired in NGT-pGDM compared to controls and further reduced in IGR-pGDM, although a more pronounced defect in insulin secretion was apparent in these women (P-index: 4.02 +/- 0.9; P < 0.05). Conclusions: Normotolerant women with pGDM show both impairment in insulin secretion and action irrespective of body weight. A more pronounced defect in insulin secretion seems to characterize normal weight women while a more prominent defect in insulin action is found in overweight women. (C) 2005 Elsevier B.V. All rights reserved.