Comment on Duran et al. Introduction of IADPSG Criteria for the Screening and Diagnosis of Gestational Diabetes Mellitus Results in Improved Pregnancy Outcomes at a Lower Cost in a Large Cohort of Pregnant Women: The St. Carlos Gestational Diabetes Study. Diabetes Care 2014;37:2442–2450

We read with interest the article by Duran et al. (1) in which the authors sought to evaluate the outcomes and the cost-effectiveness of the one-step International Association of the Diabetes and Pregnancy Study Groups (IADPSG) criteria for screening and diagnosis of gestational diabetes mellitus (GDM) compared with the two-step Carpenter-Coustan (CC) criteria. Their findings show that the IADPSG criteria increased the GDM rate (35.5% vs. 10.6%) but improved pregnancy outcomes, such as decreases in gestational hypertension, prematurity, cesarean section, and small and large for gestational age. Additionally, IADPSG criteria were estimated to save more than €14,000 per 100 women studied when compared with the CC criteria. However, a critical methodological problem has to be addressed. In their methods section, they state that for the two-step approach they performed the O’Sullivan test (50-g glucose challenge test) after a 12-h fast with no dietary restrictions. It is well known since the original description of the O’Sullivan test that it must be performed under a nonfasting state and irrespective of the time of the day (2). If positive, the next step would be to proceed with the 100-g oral glucose tolerance test and this is supported by all current clinical guidelines, recommendations, and studies in this area (3,4). The fact that this was omitted has important implications in the interpretation of the results as performing the O’Sullivan test in a fasting state could have underestimated the number of patient candidates for the second step who could potentially have been diagnosed with GDM (2–4).