Metformin is an insulin sensitiser, increasingly used in patients with type 2 diabetes who are pregnant. However, there are limited safety data available to understand the impact of metformin on the children of women who take it, with some early studies suggesting its use could be associated with increased rates of childhood obesity.

In this study, Feig and colleagues included infants of women who had participated in the MiTy randomised controlled study, where women who had a diagnosis of type 2 diabetes and were pregnant were randomised to receive either 1000mg metformin twice daily or placebo. Infants underwent anthropometric measurements at 3, 6, 12, 18 and 24 months of age.

Of the eligible children, 283 (61%) were included. At 24 months of age, there was no difference in body mass index (BMI) Z-score or mean sum of skinfold thickness between those who had received metformin and those who had not, and metformin use did not predict BMI Z-score.

These data are reassuring with regards to the early health impact of metformin use in pregnancy. However, follow-up studies are required to determine the longer term impact of metformin use in the children of women who are prescribed metformin during pregnancy.

Read the full article in Lancet Diabetes & Endocrinology doi:10.1016/S2213-8587(23)00004-9