Gestational diabetes: Implications of variation in post-partum follow-up criteria

Objective: To compare the recommendations of the American Diabetes Association (ADA) with the World Health Organization (WHO) for evaluating women with gestational diabetes (GDM) after delivery. Study design: During a 5-year period, 549 patients underwent the 2h, 75g oral glucose tolerance test (OGTT), 4-8 weeks after delivery. They were classified by the criteria of WHO (1985), the ADA [1997, fasting glucose (FPG)] and the revised WHO (1999). Results: The prevalence of diabetes by WHO-1985 and ADA-1997 were similar (8.2% versus 6.6%) but estimates of impaired glucose homeostasis varied widely (15.5% impaired glucose tolerance (IGT) versus 9.3% impaired fasting glucose, respectively). 118 (21.5%) women and 83 (15.1%) women showed a classification discrepancy between ADA-1997 with the WHO-1985 and -1999, respectively. The receiver-operating characteristic (ROC) curve area of the FPG was 0.94 for DM by the OGTT (WHO-1985 criteria) but only 0.59 for IGT by the 2h post-glucose. Conclusions: The various guidelines for GDM follow-up after delivery, often based on expert opinion, produce similar estimates for diabetes prevalence but widely discordant results for glucose intolerance. Until more uniform evidence-based criteria become available, the various strategies for GDM follow-up will continue to cause confusion in clinical practice.