Fifteen preterm babies (mean gestation: 26.7 weeks; mean birthweight 860 g) with significant glucose intolerance were treated with insulin infusions. During the insulin infusions there was a significant increase in both the mean energy intake (60.8 +/- 25.1 cal/kg per day to 79.9 +/- 24.5 cal/kg per day; P less than 0.001) and the mean amount of intravenous dextrose tolerated (7.0 +/- 2.7 mg/kg per min to 9.2 +/- 2.6 mg/kg per min; P less than 0.01). The infusions were initiated at a mean postnatal age of 5.3 days (range: 2-12 days) and were continued for 1.5-17.5 days. Of the 998 blood glucose estimations performed during the insulin infusions, 28 (2.8%) were less than 2 mmol/l and 216 (21.6%) greater than 8 mmol/l. We conclude that continuous insulin infusion is a safe and effective way of managing glucose intolerance in very low birthweight infants, provided adequate means for continuous monitoring of blood glucose are available.