15-year follow-up of recurrent "hypoglycemia" in preterm infants

Observational study of 543 infants who weighed <1850 g, published in 1988 reported seriously impaired motor and cognitive development at 18 months in those with recurrent, asymptomatic hypoglycemia (plasma glucose level ≤2.5 mmol/L on ≥3 days). No study has yet replicated this observation.

To quantify disability in a similar cohort of children followed up throughout childhood.

All children born at <32 weeks' gestation in the north of England in 1990-1991 and had laboratory blood glucose levels measured daily for the first 10 days of life.

Forty-seven index children of the 566 who survived to 2 years had a blood glucose level of ≤2.5 mmol/L on ≥3 days. All of these children and hypoglycemia-free controls, matched for hospital of care, gestation, and birth weight, were assessed at age 2. No differences in developmental progress or physical disability were detected. The families were seen again when the children were 15 years old, and 38 of the index children (81%) and matched controls agreed to detailed psychometric assessment. Findings in the 2 groups were nearly identical (mean full-scale IQ: 80.7 vs 81.2). Findings in the 21 children with a level of ≤2.5 mmol/L on ≥4 days, 7 children with a level this low on 5 days, and 11 children with a level of <2.0 mmol/L on 3 different days did not alter these conclusions.

This study found no evidence to support the belief that recurrent low blood glucose levels (≤2.5 mmol/L) in the first 10 days of life usually pose a hazard to preterm infants.