ESPE Yearbook of Paediatric Endocrinology

To read the full abstract: PLoS Med. 2019 Aug 6;16(8):e1002848. doi: 10.1371/journal.pmed.1002848.

This systematic review identified 28 randomised trials (n =3976 women) of metformin vs. insulin for treatment for gestational diabetes. Metformin use was associated with lower birth weights (overall mean difference −107.7 g), lower ponderal indices, and lower odds of macrosomia (odds ratio 0.59), but no difference in neonatal length or small for gestational age. Conversely, metformin use was associated with heavier infant weight (mean difference 440 g, 2 studies) and mid-childhood (5–9 years) BMI (mean difference 0.78 kg/m², 3 studies).

Metformin is a widely used, safe treatment option for gestational diabetes. The findings relating to birth size indicate that metformin compares well to insulin treatment, at least for these birth outcomes. However, the much fewer studies that included postnatal follow-up showed that any benefits of this reduced birth weight were reversed by a tendency to faster postnatal catch-up weight gain. The authors highlight that, in the long run, this pattern of reduced birth weight and higher postnatal catch-up may be more detrimental to offspring metabolic health than the benefits of avoiding macrosomia. Whether this is the case remains to be shown. Certainly, this review emphasises the importance of postnatal (and even longer-term) follow-up of such trials before making conclusions about the effects of maternal interventions on offspring metabolic health.