Treatment of Gestational Diabetes Mellitus and Maternal Risk of Diabetes After Pregnancy.

OBJECTIVE: To compare postpartum glucose tolerance between women treated for gestational diabetes mellitus (GDM) and those not treated. RESEARCH DESIGN AND METHODS: Metabolic testing was performed at 3 and 12 months postpartum in 599 women comprising the following gestational glucose tolerance groups: 1) normal glucose challenge test (GCT) and oral glucose tolerance test (OGTT) during pregnancy, 2) abnormal GCT with normal OGTT, 3) gestational impaired glucose tolerance, 4) mild untreated GDM, and 5) severe treated GDM. RESULTS: Birth weight progressively increased across groups 1-4 before falling steeply in treated GDM (P < 0.0001). In contrast, at 3 and 12 months, insulin sensitivity and ß-cell function progressively decreased across the five groups, mirrored by rising fasting and 2-h glucose (all P < 0.0001). Accordingly, prevalence of prediabetes/diabetes at 12 months increased in a stepwise manner across groups 1-5 (2.8%, 9.6%, 13.5%, 21.5%, and 32.6%, respectively; P < 0.0001). CONCLUSIONS: Treating GDM lowers birth weight but does not disrupt the association between gestational glycemia and maternal prediabetes/diabetes after pregnancy.