The optimal process for detecting and treating gestational diabetes mellitus (GDM) remains controversial, with wide variances in practice within and between countries. A recent pragmatic randomized controlled trial (RCT) undertaken by Hillier et al. 1 in the USA has raised renewed worldwide interest in and discussion of GDM diagnosis.The study reported no benefit at a population level in frequency of large-for-gestational-age (LGA) infants, hypertensive disorders of pregnancy, primary cesarean delivery, or a predefined composite perinatal outcome using a "one-step" diagnostic process and diagnostic criteria (primary diagnostic 75 g oral glucose tolerance test [OGTT]) as suggested in 2010 by the International Association of Diabetes in Pregnancy Study Groups (IADPSG) 2 as compared to current dominant USA-based criteria, 3 which employ a "two-step" process (initial nonfasting glucose challenge test [GCT] followed by a full OGTT if threshold glucose values are exceeded on the GCT).It should be noted that the USA criteria use very similar OGTT diagnostic thresholds to the IADPSG criteria, but require two elevated values for a GDM diagnosis. This time-honored practice lies contrary to the large body of evidence, confirmed in a recent USA-based systematic review, demonstrating that women with one abnormal value on their diagnostic OGTT carry substantially higher risks of LGA babies, cesarean delivery, pregnancy-induced hypertension, Apgar score <7, neonatal intensive care unit admission, and respiratory distress syndrome. 4 Since the IADPSG criteria classified 16.5% of women as GDM compared to an 8.5% frequency using the dominant USA criteria in the Hillier et al. study, 1 an accompanying editorial by Casey 5 concluded that the IADPSG approach offered "no apparent maternal or perinatal benefit overall." While we applaud the efforts of Hillier et al. 1 in conducting such an important study, we consider that the interpretation of the trial's results merits detailed scrutiny.
| CONSIDERATIONS REGARDING THE HILLIER ET AL. 1 TRIAL PROTOCOL AND RESULTSThe study by Hillier et al. 1 was designed and conducted as a "pragmatic RCT." The major advantages of this approach were that the study was integrated into standard care across the two Kaiser Permanente health systems involved and recruited a very substantial number of women (23 792 randomized). The investigators obtained