Treating low blood sugar prevents brain damage in newborn babies: study

Stabilising blood sugar levels in newborns with hypoglycemia, or low blood sugar, appears to prevent brain damage, according to the first study of its kind.

The study, led by the Liggins Institute at the University of Auckland in New Zealand, is published today in The New England Journal of Medicine. It was funded by the National Institutes of Health in the United States and the Health Research Council of New Zealand.

The lead researcher, Distinguished Professor Jane Harding, says the study shows that if doctors treat a baby with hypoglycemia to keep the blood sugar above a safety threshold, there is no increase in the risk of brain damage.  This threshold, already widely used, is 2.6 millimoles per litre or 47 milligrams per decilitre.

The study has also found that babies with blood sugar levels that were higher than usual appeared to be at risk of brain damage.

“Hypoglycemia is the single most preventable cause of brain damage in newborns. Up to 30 per cent of newborns are at risk, 15 per cent will be affected to at least some degree, and around 10 per cent end up admitted to intensive care,” says Professor Harding.

“We know that a baby with a blood glucose level that is too low for too long will suffer neurological damage, but there has been debate about just how low, for how long, and in which babies. This is the first clear evidence that treating babies to keep their blood sugar above a widely-used safety intervention threshold does indeed protect them.” 

The Liggins Institute researchers - working with other colleagues at the University of Auckland and the University of Waterloo - also found that babies who had blood glucose levels that rose too high or which fluctuated widely during the first 48 hours of their lives were more likely to have brain damage.

“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, but we need further studies to confirm that link,” says Professor Harding.

She says the study also shows that while there are clear benefits to the current clinical practice in many parts of the world – which is to test at-risk infants regularly - the introduction of continuous monitoring is not necessary. 

“When a glucose metre is used to monitor a baby continuously, it often picks up brief drops in glucose to below the safe level. However, we have found no link between these brief falls and any increase in neurological damage.

“Glucose is the sugar on which the brain depends most for fuel.  The main factors that put a baby at risk of low blood glucose are being born of a diabetic mother, small or large at birth, or preterm,” Professor Harding says.

When a mother has diabetes the fetus tries to compensate for her high blood glucose level by producing more insulin to clear the excess glucose from its bloodstream.  But this production of extra insulin continues once the baby is cut off from the excess glucose supply at birth, and glucose levels soon tumble.  In babies who are preterm or small at birth, the baby often cannot produce enough glucose because they lack the fat and other body stores that are used to produce it.

The Children with Hypoglycemia and their Later Development study (CHYLD) examined 404 two-year-old children who were born at risk of hypoglycemia at Waikato Hospital in Hamilton, New Zealand.  Their blood sugar levels were raised with extra food, buccal dextrose gel or intravenous dextrose if needed.

Researchers tested them at two years old for neurosensory impairment and processing difficulties – including developmental progress, cognitive and language skills, vision, hearing, physical co-ordination and executive functioning. 

The National Institutes of Health (NIH), one of the study’s funders, describes the findings as “extremely reassuring”.

“There is now firm evidence that physicians can provide an essential treatment to prevent brain damage without concern that there might be any unforeseen increase in risk to the newborn,” says Tonse Raju, M.D., Chief of the Pregnancy and Perinatology Research Branch at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development. 

The Health Research Council of New Zealand (HRC), another funder, welcomes what it calls “an exceptional piece of research”. Chief Executive Professor Kath McPherson says it fills a major gap in knowledge about the effects of low blood sugar in newborns on long-term development.

“We’re delighted to support this research, which already is leading to rethinking the treatment of low and high blood sugar in newborns in New Zealand and around the world. New Zealand punches far above its weight in research concerning paediatrics and reproductive medicine and this is another example of that excellence,” says Professor McPherson.

Research paper:
Neonatal Glycemia and Neurodevelopmental Outcomes at 2 Years

About The Liggins Institute
The Liggins Institute is one of the world’s leading centres for research on fetal and child health, nutrition, development, epigenetics and evolutionary medicine.  Our aim is to rapidly translate discoveries in basic science into therapies and strategies that will prevent or help people manage major health problems in the 21^st century.  We are based in New Zealand at the University of Auckland. www.liggins.auckland.ac.nz