J A Rowan

Dr J A Rowan, Auckland City Hospital, Auckland, New Zealand; jrowan@internet.co.nz

STUDY DESIGN

Design:

randomised controlled trial (Metformin in Gestational Diabetes [MiG] Trial).

Allocation:

{concealed}*.†

Blinding:

unblinded.†

Setting:

10 obstetric hospitals in New Zealand and Australia.

Patients:

751 women 18–45 years of age (mean age 33 y) who were 20–33-weeks pregnant with a single healthy fetus and had gestational diabetes requiring medical treatment (fasting blood glucose >97.2 mg/dl [5.4 mmol/l] or 2-h postprandial blood glucose >120.6 mg/dl [6.7 mmol/l] on >1 occasion after lifestyle intervention). Exclusion criteria included pre-pregnancy diabetes, hypertensive disorders, and ruptured membranes.

Intervention:

metformin, 500 mg once or twice daily, increased to a maximum of 2500 mg/day, with insulin added as needed (n = 373) or insulin administered according to each centre’s standard practice (n = 378). Target concentrations were <99 mg/dl (5.5 mmol/l) for fasting and <126 mg/dl (7.0 mmol/l) for 2-h postprandial blood glucose (or less).

Outcomes:

composite neonatal outcome (hypoglycaemia, respiratory distress, need for phototherapy, birth trauma, 5-min Apgar score <7, or preterm birth) and maternal hypertensive complications and weight gain. The study had 80% power to detect an absolute difference of 10% in the primary composite …