Perinatal Outcomes of Two Screening Strategies for Gestational Diabetes Mellitus: A Randomized Controlled Trial

Abstract

Objective: To evaluate differences in short-term perinatal outcomes between the two prominent screening strategies for gestational diabetes mellitus, the International Association of Diabetes and Pregnancy Study Groups (IADPSG) and Carpenter-Coustan.

Methods: In this single-site, blinded, randomized, comparative effectiveness trial, participants received a nonfasting 50-g oral glucose tolerance test and, if less than 200 mg/dL (less than 11.1 mmol/L), were randomized to further screening with either IADPSG or Carpenter-Coustan criteria. Gestational diabetes treatment occurred per routine clinical care. The primary outcome was incidence of large-for-gestational-age (LGA) neonates. Prespecified secondary outcomes included small-for-gestational-age (SGA) neonates, cesarean birth, and neonatal and maternal composites of adverse perinatal outcomes. Assuming a 15% incidence of LGA neonates in the Carpenter-Coustan group, 782 participants provided more than 80% power to detect a 7% absolute risk reduction with the use of IADPSG; planned recruitment was 920 for anticipated attrition.

Results: From June 2015 to February 2019, 1,016 participants were enrolled and 921 were randomized to IADPSG (n=461) or Carpenter-Coustan (n=460) groups. Gestational diabetes incidence (14.4% vs 4.5%, P<.001) and diabetes medication use (9.3% vs 2.4%; P<.001) were more common in the IADPSG group; there were no differences in LGA neonates, either overall (risk reduction 0.90, 97.5% CI 0.53-1.52) or among women without gestational diabetes (risk reduction 0.85, 97.5% CI 0.49-1.48). Those screened with IADPSG had higher rates of neonatal morbidity but fewer study-related adverse events. Rates of SGA neonates, cesarean birth, and maternal morbidity composite did not differ significantly between study groups.

Conclusions: The IADPSG screening criteria resulted in more women diagnosed and treated for gestational diabetes than Carpenter-Coustan without reducing the incidence of LGA birth weight or maternal or neonatal morbidity.