Metformin as a prophylactic treatment of gestational diabetes in pregnant patients with pregestational insulin resistance: A randomized study

Aim We aimed to assess the use of metformin ( MTF ) in the prevention of gestational diabetes mellitus ( GDM ) in patients with pregestational insulin resistance ( PIR ). Methods A double blind, multicenter, randomized trial was carried out in patients with a history of PIR and pregestational MTF treatment. Groups were allocated either to MTF 1700 mg/day or placebo. Patients were recruited between 12 +0 and 15 +6  gestational weeks, and treatment was extended until week 36. A multiple logistic regression analysis was applied to determine the relation between the use of metformin and the development of GDM . Results One hundred and forty one patients were randomized (68 patients in the MTF group and 73 in the placebo group). A total of 30 patients withdrew from the study during follow‐up. Administration of MTF was not associated with a decrease in the incidence of GDM as compared to placebo (37.5% vs 25.4%, respectively; P  = 0.2). Moreover, MTF administration was associated with a significant increase in drug intolerance as compared to placebo (14.3% vs 1.8%, respectively; P  = 0.02). Conclusion The use of MTF is not effective in prevention of GDM in populations with PIR . The use of MTF shows a significantly higher frequency of drug intolerance than placebo.