An important part of the management of women with gestational diabetes (GD) is their subsequent follow-up after delivery. At this postnatal visit a glucose tolerance test (GTT) is essential. We have analysed the results of the postnatal GTT's in 2,957 women whose pregnancies were complicated by GD. Diabetes mellitus was diagnosed in 59 women (2.0%) in the first 6 months after delivery. As stated in Part 1 of this paper, 31 of these 59 women may have had unrecognized prepregnancy diabetes mellitus. The significant independent predictors of postnatal diabetes mellitus on logistic regression analysis in these women were severity of GD, Asian origin and the 1-hour plasma glucose level during the antenatal GTT.