Abstract: AIM: To evaluate the safety of neonatal outcomes in women with gestational diabetes mellitus(GDM) treated with metformin or insulin. METHODS: Randomized controlled trials (RCTs) about the clinical risks of metformin vs insulin on neonatal outcomes in women with GDM were retrieved on the Cochrane library, Pubmed, Web of knowledge, VIP, CNKI and Wangfang. The trials were screened according to the inclusion and exclusion criteria by two reviewers independently, the data were extracted, the methodological quality was assessed, and finally meta-analysis was performed by Rev Man5.2 software. RESULTS: A total of seven RCTs included 1 564 GDM patients. The incidence risk of neonatal hypoglycemia of metformin decreased 64% [95%CI: (0.46, 0.88)] compared with that in insulin. There were no significant differences in birthweight, gestational age, pH of umbilical artery, the incidence rate of hyperbilirubinemia or respiratory distress syndrome (RDS) between metformin and insulin. CONCLUSION: Metformin could associated with a decreased incidence risk of neonatal hypoglycemia and might be safe in newborn of women with GDM.

Key words: insulin, neonatal, metformin, gestational diabetes mellitus, systematic review