Objective: To systematically review the evidence for screening for gestational diabetes mellitus (GDM).
Data sources: We established eligibility criteria for relevant studies. We systematically searched MEDLINE and the Cochrane Collaboration Library for studies meeting eligibility criteria. We supplemented this search with further studies identified from reference lists of reviews.
Methods of study selection: Two reviewers examined each article for eligibility. A single reviewer abstracted relevant data from the included articles; a second reviewer checked the abstractions. We graded the quality of the articles according to criteria developed by the U.S. Preventive Services Task Force.
Tabulation, integration, and results: No well-conducted, randomized, controlled trial provides direct evidence for the health benefits of screening for GDM. The evidence is unclear regarding the optimal screening and reference diagnostic test for GDM. The impact of hyperglycemia on adverse maternal and neonatal health outcomes is probably continuous. Although insulin therapy decreases the incidence of fetal macrosomia for those women with more severe degrees of hyperglycemia, the magnitude of any effect on maternal and neonatal health outcomes is not clear. The evidence is insufficient to determine the magnitude of health benefit for any treatment among the large number of women with GDM at milder degrees of hyperglycemia. We found limited evidence regarding the potential adverse effects of screening for GDM.
Conclusion: Because of the lack of high-quality evidence concerning critical issues, we are unable to determine the extent to which screening has an important impact on maternal and neonatal health outcomes. A randomized, controlled trial of screening is necessary to answer the many remaining questions.