A follow-up of a randomised study of metformin and insulin in gestational diabetes mellitus: growth and development of the children at the age of 18 months.

OBJECTIVE: To compare the growth and development of children born to mothers with gestational diabetes mellitus (GDM) requiring pharmacological treatment, and randomised to treatment with metformin or insulin. DESIGN: Follow-up of a randomised controlled trial (RCT) comparing metformin and insulin treatment of GDM. SETTING: Data were gathered during routine visits to child welfare clinics at the ages of 6, 12, and 18 months, including weight and height measurements, and assessment of motor, social, and linguistic development. SAMPLE: The children of mothers with GDM randomised to metformin (n = 47) or insulin (n = 50) treatment during pregnancy. METHODS: Data were collected from the structured questionnaire filled in at the child welfare clinics. MAIN OUTCOME MEASURES: The growth and development of the children until the age of 18 months. RESULTS: Children exposed to metformin were significantly heavier (10.47 versus 9.85 kg, 95% CI 0.04-1.20) at the age of 12 months and taller and heavier (83.9 vs 82.2 cm, 95% CI 0.23-3.03, 12.05 vs 11.32 kg, 95% CI 0.04-1.43) at the age of 18 months. The mean ponderal index (PI) did not differ significantly. The motor, social, or linguistic development evaluated at the age of 18 months did not differ between the groups. CONCLUSIONS: Children prenatally exposed to metformin were heavier at the 12 months measurements and taller and heavier at the 18 months measurements than those exposed to insulin, but their body composition defined by PI did not differ. Over the short term, metformin does not seem to be harmful with regards to early motor, linguistic, or social development.

Metformin should be considered in the treatment of gestational diabetes: a prospective randomised study.

OBJECTIVE: To examine if oral metformin is as effective as insulin in the prevention of fetal macrosomy in pregnancies complicated with gestational diabetes mellitus (GDM). DESIGN: Open-label prospective randomised controlled study. SETTING: Maternity outpatient clinics in a secondary and tertiary level hospital in Finland. SAMPLE: One hundred women with GDM who did not attain euglycaemia with diet. METHODS: Women were randomised to therapy with insulin (n = 50) or oral metformin (n = 50). MAIN OUTCOME MEASURES: Incidence of large-for-gestational-age (LGA) infants and neonatal morbidity. RESULTS: There were no statistically significant differences in the incidence of LGA (8.5 versus 10.0%, P = 0.97), mean birthweight, mean cord artery pH or neonatal morbidity between the insulin and metformin groups. Fifteen (31.9%) of the 47 women randomised to metformin needed supplemental insulin. They were more obese (with a body mass index of 36 versus 30 kg/m(2), P = 0.002), had higher fasting blood glucose levels in an oral glucose tolerance test (6.1 versus 5.0 mmol/l, P = 0.001) and needed medical treatment for GDM earlier (26 versus 31 gestational weeks, P = 0.002) than women who were normoglycemic with metformin. There was a tendency to a higher rate of caesarean sections in the metformin group than in the insulin group (RR 1.9; 95% CI 0.99-3.71). CONCLUSIONS: Metformin seems to be suitable for the prevention of fetal macrosomy, especially in lean or moderately overweight women developing GDM in late gestation. Women with considerable obesity, high fasting blood glucose and an early need for pharmacological treatment may be more suitable for insulin therapy.