Potential of Metformin to Improve Cardiac Risk in Postpartum Women with Gestational Diabetes

Objective: Pregnancy is associated with an increase in total cholesterol, high density lipoproteins (HDL), and low-density lipoproteins (LDL). Postpartum, HDL and LDL decrease over the first 12 weeks postpartum. Oxidized LDL (ox-LDL) is a marker of oxidative stress-related inflammation, which is associated with obesity and also with development of cardiovascular disease. Cardiovascular protection and weight loss are benefits from metformin, especially in women with diabetes. The objective of this study was to compare changes in lipid profiles and biomarkers for obesity during the initial 6 weeks postpartum between women with gestational diabetes mellitus (GDM) treated with metformin versus placebo.

Methods: This was a planned ancillary study of a randomized controlled trial compares metformin versus placebo in women with GDM for postpartum weight loss. Two 3 mL blood samples were collected within 24 h of delivery and 6 weeks postpartum immediately processed after collection then stored at -20°C until completion of clinical trial prior to analysis. Change in the median plasma concentrations of total cholesterol, HDL, ox-LDL, glucose, insulin, leptin, and unacylated ghrelin were compared between study groups.

Results: Of the 77 postpartum women were included, 35 received metformin and 42 received placebo. There was less of a reduction in HDL in the metformin group compared to placebo (-2.3 versus -7.5 mg/dL, p = 0.019). In addition, there was a greater reduction in ox-LDL in those receiving metformin (-12.2 versus -3.8 mg/dL, p = 0.038). No other differences were observed in the selected biomarkers evaluated.

Conclusion: Biomarker levels of HDL and ox-LDL were positively affected during the initial 6 weeks postpartum in GDM women treated with metformin. Additional studies with a longer duration of metformin treatment in the postpartum period are warranted to evaluate long-term potential benefits.