A newborn condition affecting one in six babies has been linked to impairment in some high-level brain functions that shows up by age 4.5 years.
Researchers found that children who had experienced low blood sugar levels as newborns were two to three times more likely to have difficulties with executive function (skills for problem-solving, planning, memory and attention) and visual-motor co-ordination (skills for fine control of movement, and understanding what you see) at age 4.5 years than children who had normal blood sugar levels.
Overall, the lower the blood sugar levels, or the more often they dropped, the greater the impairment was. Strikingly, children who had experienced a drop in blood sugar that was not detected using routine blood sugar monitoring were four times more likely to have difficulties with these skills – the first time this has been shown.
There was no link with lowered intelligence as measured by IQ.
The findings, published in top-ranking journal JAMA Pediatrics, are the latest from a major long-term study, dubbed the “CHYLD” study (Children with Hypoglycaemia and their Later Development), by an international research team led by Distinguished Professor Jane Harding at the University of Auckland-based Liggins Institute.
The team includes researchers from the Liggins Institute, the University of Auckland, Waikato Hospital, the University of Canterbury and the University of Waterloo. They are following 614 New Zealand babies born at risk of low blood sugar levels (neonatal hypoglycaemia) into childhood to see if the condition affects their later growth and development.
Low blood sugar affects up to 15 percent of all babies, and is the only common preventable cause of brain damage in infancy. At-risk babies – up to a third of all born - are those born premature, smaller or larger than usual and babies whose mothers have diabetes.
Health guidelines say at-risk babies should be tested with heel-prick blood tests in the first few hours after birth. If their blood sugar is too low, they are treated with dextrose (sugar) gel to return it to normal levels – a breakthrough treatment pioneered in 2013 by Professor Harding and her team.