Early Detection of Insulin Sensitivity and β-Cell Function with Simple Tests Indicates Future Derangements in Late Pregnancy

Objective: Insulin sensitivity and secretion during early and late pregnancy were assessed in women with normal glucose tolerance and gestational diabetes mellitus (GDM). Research Design and Methods: The oral glucose tolerance test (OGTT) was performed in 903 women at 16–20th gestational week, of whom 37 had GDM (GDM1 group), and 859 repeated the OGTT at wk 26–30. At the second test, 55 had GDM (GDM2 group); the others remained normotolerant (ND group). Insulin sensitivity from OGTT (as quantitative insulin sensitivity check index and OGTT insulin sensitivity) and β-cell function (as the ratio of the areas under the insulin and glucose concentration curves, adjusted for insulin sensitivity) were assessed in both tests. Results: In early pregnancy the quantitative insulin sensitivity check index was not different in the three groups, whereas OGTT insulin sensitivity was lowest in GDM2, intermediate in GDM1, and highest in ND. In late pregnancy both indices were reduced in GDM compared with ND and lower tha...