Impact of gestational diabetes mellitus screening strategies on perinatal outcomes: a simulation study

To evaluate the impact on perinatal outcomes of universal gestational diabetes (GDM) screening based on 1999 WHO and IADPSG diagnostic criteria; to assess the quality of the evidence (GRADE) to support GDM screening.

Simulation of a hypothetical cohort of community-based pregnant women with 10% GDM prevalence (1999 WHO). Most parameters were obtained from recent systematic reviews.

Compared to no screening, screening based on 1999 WHO criteria (followed by treatment) reduced the incidence of large for gestational age (LGA) neonates by 0.53% (95% CI 0.37-0.74%; NNS=189) and of preeclampsia by 0.27% (0.10-0.45%; NNS=376). Screening based on IADPSG criteria reduced incidences by 0.85% (0.54-1.29%; NNS=117) and by 0.39% (0.15-0.65%; NNS=257), respectively. Compared to screening based on 1999 WHO criteria, screening with IADPSG criteria reduced the incidence of LGA by 0.32% (0.09-0.63%; NNS=309) and of preeclampsia by 0.12% (0.01-0.25; NNS=808). The quality of evidence for both screening approaches is very low.

Universal screening for GDM has only a modest impact on pregnancy outcomes. The impact of screening based on IADPSG (vs. WHO, 1999) criteria is slightly larger. However, costs and resources should also be considered in local selection of a screening approach.