The role of pancreatic insulin secretion in neonatal glucoregulation. II. Infants with disordered blood glucose homoeostasis.

Some neonates, such as those who are preterm or small for dates, become hypoglycaemic or hyperglycaemic. These disorders represent a failure of neonatal metabolic adaptation, but the underlying mechanisms are unclear. Data from studies of hypoglycaemic and hyperglycaemic infants were reviewed in the light of new data from studies of healthy neonates. Data from 28 neonates, who had disordered blood glucose homoeostasis, were analysed to determine the interrelationships between circulating concentrations of glucose, intermediary metabolites, glucagon and insulin, and glucose production rates. Blood glucose concentrations ranged from 2.5 to 26.1 mmol/l, and glucose production rates from 0 to 19.2 mg/kg/min. Blood glucose concentrations were positively related to intravenous glucose infusion rates and to glucose production rates. A negative relationship existed between plasma glucagon and blood glucose concentrations, but there was a wide variation in plasma insulin levels at all blood glucose concentrations. No relationship between either plasma insulin or glucagon concentration and glucose production rate was shown. It is concluded that in neonates with disordered blood glucose homoeostasis, blood glucose concentration is influenced by the rate of administration of glucose, with less precise internal control mechanisms than older subjects. This emphasises the importance of blood glucose monitoring and careful prescribing of exogenous glucose by clinicians caring for such infants.