Diagnosis of Gestational Diabetes Mellitus: It Is Time for International Consensus

Abstract

Gestational diabetes mellitus (GDM)2 has been defined as any degree of glucose intolerance with an onset or first recognition during pregnancy (1–3). Fetal complications of GDM include macrosomia (large baby, which leads to birth injuries), shoulder dystocia, and neonatal hypoglycemia, and adverse outcomes for the mother are an increased risk of cesarean delivery, preeclampsia, and hypertension during pregnancy, as well as a significantly higher risk of subsequent type 2 diabetes. Treating women with GDM reduces at least some of the adverse outcomes (4). Estimates of the prevalence of GDM range from <1% to 28%, reflecting the different diagnostic criteria and populations studied. The increasing prevalence of GDM in the US is congruent with the marked increase in obesity and type 2 diabetes. Pregnant women have been evaluated for diabetes for more than 50 years. Notwithstanding the 5 international workshops devoted to GDM that have been held between 1979 and 2005, there is lack of agreement concerning the optimal method to identify “any degree of glucose intolerance.” The criteria for both screening and diagnosing GDM vary considerably among countries and often between diabetes and obstetric organizations in a single country (5). Screening recommendations range from none (do not screen) to selective (screen only those at high risk) to universal. Approaches for screening tests include fasting glucose, random glucose, or, more commonly, a glucose challenge in which the patient ingests 50 g glucose (regardless of the time of the last meal). If the 1-h postload plasma glucose concentration exceeds the threshold, a full diagnostic oral glucose tolerance test (OGTT) is performed; however, 2 thresholds [140 mg/dL (7.8 mmol/L) or 130 mg/dL (7.2 mmol/L)] are generally used. Approximately 15% of women have concentrations that exceed the higher cutoff, which identifies approximately 80% of women with GDM, whereas the use of …