Real-World Experience of Adding Metformin in Pregnant Women with Type 1 Diabetes in a Chinese Population: A Retrospective Cohort

INTRODUCTION: Glycemic control in pregnant women with type 1 diabetes (T1D) is challenging with only insulin, and the incidence rate of adverse perinatal outcomes is high. Increasing data have indicated the safety and effect of metformin in pregnancy; however, no relevant data are available in pregnant women with T1D. We aimed to investigate glycemic control and perinatal outcomes in pregnant women with T1D in a Chinese population and explored the role of metformin in these patients. METHODS: We obtained data of 38 pregnant women with T1D who received regular antenatal care and delivered at Peking Union Medical College Hospital (PUMCH) between 1 January 2006 and 31 May 2018. The perinatal outcomes of T1D patients who added metformin as adjunct treatment and those who remained on insulin-alone therapy were compared retrospectively. RESULTS: Being overweight was common (35.1%) in pregnant women with T1D. On average, the insulin dose increased by 35.30 ± 22.60 unit/day during pregnancy. The cesarean delivery rate was high (65.8%), and fetal macrosomia was the main reason. The change of HbA1c in the metformin-insulin group was more prominent than in the insulin-only group (− 1.47 ± 1.17% vs. − 0.90 ± 1.13%, p = 0.05). There was no statistically significant difference in perinatal outcomes between the two groups. CONCLUSIONS: The incidence of adverse perinatal outcomes in pregnant women with T1D was high. This study innovatively suggested that metformin could be safe and could contribute to improving glucose management in pregnant women with T1D.