Pregnancy outcomes not improved with 1-step testing versus 2-step testing for gestational diabetes

Reference

Brady M, Hensel DM, Paul R, et al. One-step compared with two-step gestational diabetes screening and pregnancy outcomes. Obstet Gynecol 2022;150(5):712-723.

Synopsis

These authors conducted a meta-analysis to compare outcomes for mothers and infants with 1-step testing (using the International Association of Diabetes in Pregnancy Study Group criteria) versus standard 2-step testing (Carpenter-Coustan). A positive 1-step test was a 75g oral glucose test with results exceeding any one of the following glucose thresholds: 92 g/dL fasting, 180 g/dL at 1 hour, 155 g/dL at 2 hours, and 140 g/dL at 3 hours. The authors included 4 randomized controlled trials (RCTs; 24,966 mothers) and 13 population-based observational studies (710,677 mothers). All RCTs were conducted in US academic centers (with a higher prevalence of gestational diabetes [GDM] diagnoses and other complications) and the observational studies were more international, with some community-based studies (with a lower prevalence). The authors conducted meta-analyses of the RCTs and observational studies separately. The meta-analysis of the RCTs found no difference in the main outcome of large-for-gestational-age neonates (relative risk [RR] 0.95; 95% CI 0.88 - 1.04). Patients who underwent 1-step testing were more likely to be diagnosed with GDM (16.3% vs 8.3%; RR 2.13; 1.61 - 2.82, number needed to screen [NNS] = 13) and to be treated with diabetes medications (7.1% vs 3.8%; RR 2.24; 1.21 - 4.45; NNS = 31). One-step testing was also more likely to be associated with neonatal intensive care unit admission (5.1% vs 4.5%; RR 1.21;1.00 - 1.26; NNS = 167) and neonatal hypoglycemia, defined as less than 40 g/dL at any time within 24 hours after birth (3.0% vs 7.6%; RR 1.23; 1.13 - 1.34; NNS = 59). The meta-analysis of observational studies yielded similar results. In a sensitivity analysis including only the RCTs and observational studies with a quality score in the top quartile (363,959 mothers), the authors found a small reduction in the rate of large-for-gestational-age infants (RR 0.97; 0.95 - 0.98) but otherwise similar results.