Treating Low Blood Sugar in Newborns

The investigators examined the association between blood glucose levels in newborns and brain function at 2 years of age.Jupiterimages/Stockbyte/Thinkstock

A newborn’s brain relies on glucose to fuel development. Low blood glucose levels (hypoglycemia) at birth have been associated with brain injury and intellectual and developmental disabilities. Infants are typically screened at birth for low blood glucose, which is common and easily treated. However, clear evidence to support a specific threshold for hypoglycemia treatment has been lacking.

An international team led by Dr. Jane E. Harding of the University of Auckland, New Zealand, examined the relationship between glucose concentrations in newborns and subsequent brain function at 2 years of age. The research was funded in part by NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). Results appeared on October 15, 2015, in the New England Journal of Medicine.

The researchers followed 404 newborns at a hospital in New Zealand. All were born at risk of hypoglycemia, mainly because the mother had diabetes, the birth was preterm (before 37 weeks), or the birth weight was very low or very high.

Of the infants, 216 (53%) had blood glucose levels less than 47 milligrams per deciliter (mg/dl), which is a well-accepted threshold for hypoglycemia. These infants were treated with a combination of additional feedings and oral or intravenous glucose to maintain their blood sugar above this threshold. Hospital staff periodically monitored the infants’ blood glucose for up to 48 hours. The researchers also fitted the infants with a device that continuously monitored their blood glucose every 5 minutes. (This information was not available to the hospital staff.)

The researchers assessed the children’s neurosensory functions at 2 years of age. These included developmental progress, cognitive and language skills, vision, hearing, physical coordination, and executive functioning (ability to concentrate and carry out age-appropriate tasks). Infants treated for hypoglycemia fared similarly in these areas to the infants who didn’t need treatment for hypoglycemia. The continuous glucose monitoring revealed that episodes of low blood glucose were common in both the treated infants and in those thought to have normal blood glucose levels. These episodes weren’t detected with standard intermittent blood glucose testing and weren’t associated with neurosensory impairment.

The scientists found that neurosensory impairment was more likely at age 2 if infant glucose levels had fluctuated widely or were higher during the first 48 hours after birth. “It may be that it’s not only important to keep blood glucose levels from dropping too low, but also to keep them from swinging too high, too fast,” Harding says.

The team is reassessing the children for neurosensory impairment at around age 4 to see if the effects of hypoglycemia might emerge later in development. They are also exploring therapies to maintain blood glucose levels at a safe, stable concentration.