ESPE Yearbook of Paediatric Endocrinology

J Pediatr. 2020 Aug;223:34–41.e4. doi: 10.1016/j.jpeds.2020.02.079. PMID: 32381469.

In this study, the plasma and interstitial (GCMS) glucose levels were measured in term healthy newborns for a period of 5 days to understand the changes in the glucose levels after birth. The findings suggest that in normal term healthy newborns if hypoglycaemia persists after the 4th day of life, then further investigations are needed to rule out other causes of persistent hypoglycaemia.

Immediately after birth, blood glucose concentrations drop in the newborn due to the abrupt cessation of glucose delivery from the placenta. This drop in blood glucose triggers a counter regulatory responses to restore the blood glucose to normal values. These counter regulatory responses include reduction in beta cell insulin release, increase in alpha cell glucagon, increase in cortisol and growth hormone secretion, increases in adrenaline and noradrenaline, activation of glycogenolysis, gluconeogenesis, lipolysis and ketogenesis. This phase of transition from birth to the time when blood glucose levels stabilize is called transitional neonatal hypoglycaemia.

Based on the findings of this GLOW study, the period of transitional neonatal hypoglycaemia is around 4 days in normal healthy mostly breast-fed infants after which the blood glucose levels stabilize to normal values. Even in these normal healthy term infants the patterns of glucose concentrations varied widely (with many babies having glucose levels below the accepted thresholds for treatment of hypoglycemia) during the transition phase. These observations suggest that in normal term healthy newborns, if hypoglycaemia persists after the 4th day of life then they will need further investigations to rule out other causes of persistent hypoglycaemia. However, it is important to note that these observations are based only on term healthy newborns who are not at risk of any persistent hypoglycaemia condition. Newborns at risk of any persistent hypoglycaemia condition may require early intervention and management of the hypoglycaemia and not wait until day 4 of life.