Oral contraceptives and insulin receptor binding in normal women and those with previous gestational diabetes

The effect of a low-dose triphasic oral contraceptive (ethinyl estradiol and levonorgestrel) on glucose tolerance, plasma insulin response to a glucose challenge, and insulin receptor binding to monocytes and erythrocytes was investigated in seven women with previous gestational diabetes and seven nondiabetic control subjects. Investigations were performed in the luteal phase before the hormonal intake and after hormonal treatment for 2 and 6 months. Before treatment, women with previous gestational diabetes had significantly impaired glucose tolerance (p less than 0.05) when compared with the healthy controls, but no differences in insulin receptor binding were observed. Glucose tolerance and the insulin response to oral glucose remained unchanged in both groups during the treatment period. In the control subjects a significant decrease (p less than 0.05) in insulin receptor binding to monocytes was observed after hormonal intake for 6 months whereas the insulin receptor binding remained unchanged in the women with previous gestational diabetes. No correlation was found between the receptor binding data obtained from monocytes and erythrocytes in either group of women. The study demonstrates that in lean nondiabetic women and women with previous gestational diabetes of normal weight without first-degree history of diabetes there is no apparent direct association between glucose tolerance, plasma insulin levels, and insulin binding to erythrocytes and monocytes during intake of low-dose oral contraceptives.