Decreased Insulin Secretion in Women with Previous Gestational Diabetes Mellitus

Objectives: Gestational diabetes mellitus (GDM) affects 2%–4% of the all pregnant women, and it is a major risk factor for development of type 2 DM. We performed this cross-sectional study to determine whether there were defects in insulin secretory capacity or insulin sensitivity in women with previous GDM. Methods: On 6–8 weeks after delivery, 75 g oral glucose tolerance test was performed in 36 women with previous GDM and 19 non-pregnant control women matched with age and weight. Intravenous glucose tolerance test was performed on 10–14 weeks after delivery. Insulin secretory capacity measured as the acute insulin response to glucose (AIRg) and insulin sensitivity as minimal model derived sensitivity index (SI) were obtained. AIRg×SI (β-cell disposition index) was used as an index of β-cell function. Results: Women with previous GDM were classified into normal glucose tolerance (postpartum-NGT, n=19) and impaired glucose tolerance (postpartum-IGT, n=17). Postpartum fasting glucose levels were significantly higher in postpartum-IGT compared to postpartum-NGT and control (P<0.05). AIRg×SI was significantly lower in postpartum-IGT compared to control (P<0.05). SI was lower in postpartum-NGT and postpartum-IGT compared to control, but the difference did not have the statistical significance. Frequency of parental history of type 2 diabetes was significantly greater in postpartum-IGT compared to postpartum-NGT (P<0.05). Conclusion: Women with previous GDM showed impaired insulin secretion although their glucose tolerance states were restored to normal. It suggests impaired early insulin secretion may be a major pathophysiologic factor for development of type 2 DM, and this defect may be genetically determined. (Ewha Med J 2015;38(1):30-35)