One step or two to diagnose gestational diabetes?

Experts convened by the National Institutes of Health for a Consensus Development Conference on Diagnosing Gestational Diabetes Mellitus (GDM) have proposed maintaining the current 2-step approach to diagnosis rather than a 1-step process. The panel, comprising 15 experts and 19 speakers, met March 4-9 in Bethesda to examine a report prepared through the Agency for Healthcare Research and Quality’s Evidence-based Practice Centers program. The assessment was sponsored by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the Office of Disease Prevention.

The 1-step approach to diagnosing GDM, a determination made based on 1 abnormal value, was proposed by the International Association of Diabetes and Pregnancy Study Groups (IADPSG). Currently a 2-step approach is used in the United States: a challenge test followed by a tolerance test, if needed. That approach is recommended by the American College of Obstetricians and Gynecologists.

The NIH panel noted that “despite the near uniformity of current practice in the United States, a number of controversies remain: the value of routine screening, the most appropriate method and glycemic thresholds for diagnosis, and the effects of treatment on the short- and long-term outcomes for women and their children.”

After examining the evidence, the NIH panel determined that the evidence is insufficient to adopt a 1-step approach. In its draft statement of March 6, the panel pointed out that the IADPSG 1-step strategy “would increase the number of women labeled as GDM two- to threefold and could increase personal and societal costs.” A diagnosis of GDM is inconvenient and anxiety-provoking as well as costly, they note in the report, and would result in a greatly increased workload (approximately 30%) for doctors, dieticians, and diabetes educators who work with women with GDM.

Evidence also exists, the panel noted, that labeling more women as having GDM may increase the incidence of cesarean delivery and prenatal testing.