Retrospective Cohort Study Evaluating the Impact of Metformin on Hypertensive Disorders of Pregnancy in A2GDM

Metformin, although traditionally used in the setting of insulin resistance, is also thought to have anti-inflammatory properties that support vasculature and placental tissue development in pregnancy. We sought to evaluate the impact of metformin on hypertensive disorders of pregnancy. This is a retrospective cohort study of gestational diabetics treated with medication (A2GDM) who received care at a large tertiary care institution. Inclusion criteria were delivery between 1/1/2013 – 12/31/2019 and A2GDM diagnosed in the third trimester. Exclusion criteria were pregestational diabetes and metformin use prior to pregnancy. We compared those with A2GDM not on metformin to those with A2GDM on metformin. Use and dose of medication was determined through chart review. Primary outcome was hypertensive disorders of pregnancy (gestational hypertension or mild and severe preeclampsia). Demographics were compared with Wilcoxon rank sum or chi-squared tests. Outcomes were compared using logistic regression adjusting for potential confounders. 1284 met inclusion criteria: 626 (48.8%) A2GDM not on metformin and 658 (51.2%) on metformin. Significant demographic differences included body mass index being lower in those taking metformin (p = 0.02), and higher aspirin use in those taking metformin (p < 0.001, Table 1). Rate of hypertensive disorders of pregnancy was 106 (16.9%) in A2GDM not on metformin and 102 (15.5%) in A2GDM on metformin (aOR = 0.89 (0.63 – 1.26), p = 0.51, Table 2). When comparing outcomes based on metformin dose, primary outcome was significantly lower in A2GDM on 1000mg of metformin than A2GDM not on metformin (aOR = 0.65 (0.42 – 0.97), p < 0.001, Figure 1). A2GDM with metformin use was associated with fewer NICU admissions, neonatal hypoglycemia and hyperbilirubinemia (Table 2). Metformin use in A2GDM demonstrates a dose dependent reduction in hypertensive disorders of pregnancy, requiring at least 1000mg for reduction. These results should be confirmed in a randomized trial.View Large Image Figure ViewerDownload Hi-res image Download (PPT)