Tight versus less tight glycaemic targets for women with gestational diabetes mellitus: a randomised controlled trial

To determine if tight glycemic control in gestational diabetes mellitus (GDM) reduces adverse outcomes compared to less tight targets.

In a single-center, open-label randomized controlled trial, 650 women with GDM (singleton pregnancies, 12-31 weeks' gestation) were randomized to tight (fasting < 5.1 mmol/L, 1-h postprandial < 7.0 mmol/L) or less tight (fasting < 5.3 mmol/L, postprandial < 7.8 mmol/L) targets. The primary outcome was the incidence of large-for-gestational-age (LGA) infants. Secondary outcomes included measures of maternal and neonatal health, analyzed by intention-to-treat.

Of 650 enrolled women, 626 (96.3%) completed the trial with primary outcome data. The tight-target group had a lower incidence of LGA (19.2% vs. 26.5%; adjusted relative risk (aRR) 0.61, 95%CI 0.42-0.89; p = 0.010), lower cesarean rates (23% vs. 29.9%; aRR 0.63; p = 0.012), and reduced gestational weight gain (10.1 vs. 10.7 kg; p = 0.006). Insulin use was higher with tight targets (32.6% vs. 21.6%; aRR 1.67; p = 0.005). Serious complications and maternal hypoglycemia rates were low and comparable.

Tight glycemic targets in GDM lower the risk of LGA births, cesarean delivery, and excess maternal weight gain without increasing severe adverse events, though they necessitate more frequent insulin therapy.