Transient low blood glucose levels in neonates are common, as the source of glucose at delivery changes from a continuous supply from the mother to the intermittent supply from feeds. It is estimated that 10 percent of normal term newborns cannot maintain a plasma glucose concentration above 30 mg/dL (1.7 mmol/L) if their first feeding is delayed for three to six hours after birth [1,2]. Although transient asymptomatic hypoglycemia in healthy infants appears to be part of the normal transition to extrauterine life, persistent or recurrent hypoglycemia can result in neurologic sequelae. (See 'Neurodevelopmental outcome' below.)
The pathogenesis, clinical manifestations, evaluation, and management of neonatal hypoglycemia will be discussed here.
It has been difficult to define pathologic neonatal hypoglycemia as a precise numerical blood glucose level. Low blood glucose levels normally occur after birth, and most infants are asymptomatic despite very low blood glucose levels. However, some infants are symptomatic at the same or even higher blood glucose levels. This variability is due to a number of factors that affect the infant’s response to a decrease in blood glucose level, including the infant’s gestational age, postnatal age, the presence of other sources of energy (eg, ketone bodies), and other factors that affect glucose metabolism. Thus, the diagnosis of clinically significant hypoglycemia is dependent on the clinical setting and cannot solely be based on a specific blood glucose level.
Ideally, neonatal hypoglycemia would be defined as the blood glucose concentration at which intervention should be initiated to avoid significant morbidity, especially neurologic sequelae. However, this definition remains elusive because the blood glucose level and duration of hypoglycemia associated with poor neurodevelopmental outcome has not been established [3,4]. (See 'Neurodevelopmental outcome' below.)
In 2000, a consensus statement proposed the use of practical operational thresholds for glucose concentrations at which intervention should be considered . These values would provide a margin of safety for the management of neonatal hypoglycemia. (See 'Management' below.)