Screening for gestational diabetes mellitus: one step versus two step approach. A meta-analysis of randomized trials.

Objective: Worldwide controversy exists regarding the best approach and criteria for gestational diabetes mellitus (GDM) screening and diagnosis. The aim of this systematic review and meta-analysis of randomized trials was to assess the incidence of maternal and neonatal outcomes comparing the one step with the two step approach for the diagnosis of GDM. Methods: Electronic databases were searched from their inception until June 2018. We included all the randomized trials comparing the one step versus the two step method for screening and diagnosis of GDM. The primary outcome was the incidence of large for gestational age (LGA), defined as birth weight >90th percentile. Meta-analysis was performed using the random effects model of DerSimonian and Laird, to produce summary treatment effects in terms of relative risk (RR) with 95% confidence interval (CI). Results: Four randomized clinical trials (RCTs) ( n  = 2582 participants) were identified as relevant and included in the meta-analysis. Women screened with the one step approach had a significantly lower risk of adverse perinatal outcomes, including LGA (RR 0.46, 95% CI 0.25-0.83), admission to neonatal intensive care unit (NICU) (RR 0.49, 95% CI 0.29-0.84) and neonatal hypoglycemia (RR 0.52, 95% CI 0.28-0.95), compared to those randomized to the screening with the two step approach. The one step approach was also associated with lower mean birth weight (mean difference -112.91 grams, 95% CI -190.48 to -35.33). No significant difference in the incidence of GDM was found comparing the one step versus the two step approach (8.3 versus 4.4%; RR 1.60, 95% CI 0.93-2.75). Conclusions: This study provides high quality evidence that the diagnosis of GDM by the one step approach is associated with better perinatal outcomes, including lower incidences of LGA, NICU admission and neonatal hypoglycemia, compared to the two step approach. Based on these findings, we recommend screening of GDM using the one-step approach.