We undertook this study to determine the incidence of diabetes mellitus (DM) and impaired glucose tolerance (IGT) after gestational diabetic mellitus (GDM). It is a follow-up study of a consecutive sample of women with GDM in a tertiary care center in Trinidad, West Indies. The cohort was a consecutive sample of 157 women with GDM who delivered in the hospital between June 1981 and December 1984. Of these, a volunteer sample of 60 women (38%) consented to participate 3.5-6.5 yr later. The two groups were remarkably similar in ethnic composition, mean age at index delivery, marital status, and family history of DM. Interviews revealed that 26 women (43%) had already developed DM for which they were receiving treatment. The remaining 34 women (57%) were given a 2-h 75-g oral glucose tolerance test, and fasting and half-hourly venous blood samples were obtained and analyzed for plasma glucose. Based on accepted diagnostic criteria, 11 (32%) of 34 had DM, 10 (29%) had IGT, and 13 (38%) had normal glucose tolerance. A total of 37 (62%) of 60 women had developed DM, and another 10 (17%) had IGT in the intervening 3.5-6.5 yr. The results support findings that GDM is associated with an increased risk of mothers developing DM in later life.
