Relationship between Measures of Neonatal Glycemia, Neonatal Illness, and 2-Year Outcomes in Very Preterm Infants

Abstract

Objectives: To investigate relationships between early neonatal glycemia, neonatal characteristics, neonatal illness, and developmental outcomes in very preterm infants.

Study design: A retrospective, observational cohort study of 443 infants born weighing <1500 g or <30 weeks of gestation, and admitted within 24 hours to National Women's Hospital, Auckland, New Zealand. Glucose variability was defined as the standard deviation around the mean after log transformation of all blood glucose concentrations. Absolute glycemic excursions in the first week were used to divide the infants into 4 groups: normoglycemic; hypoglycemic; hyperglycemic, and unstable.

Results: Compared with normoglycemic infants, hypoglycemic and unstable infants had lower birth weight z-scores, and hyperglycemic and unstable infants were of lower birth weight. Hypoglycemic infants had similar outcomes to normoglycemic infants. Hyperglycemic and unstable infants were less likely to survive without neonatal morbidity and less likely to survive without neurodevelopmental impairment at 2 years of age. Higher mean blood glucose concentration was seen in the hyperglycemic and unstable groups, and was associated with worse neonatal and 2-year outcomes. Greater glucose variability was seen in the hypoglycemic and unstable groups, and was associated with worse neonatal illness but not outcome at 2 years. No associations between measures of neonatal glycemia and neonatal or 2-year outcomes remained after correction for gestation, birth weight z-score, and socioeconomic status.

Conclusions: In very preterm infants, measures of neonatal glycemia are markers of gestational age and intrauterine growth, and are not independent predictors of neonatal illness or outcomes at 2 years of age.

Keywords: glucose variability; hyperglycemia; hypoglycemia; neurodevelopment; preterm infant.