Premature babies are particularly at risk
Many babies suffer from hypoglycaemia in the days after birth, as their bodies struggle to adjust to a world outside the womb which lacks a constant supply of food.
Some babies are thought to be more vulnerable than others - perhaps for genetic reasons - and premature or very tiny babies are also more likely to experience blood sugar problems.
However, scientists from Johns Hopkins Children's Centre in Baltimore, US, and the St Christopher's Hospital for Children in Philadelphia have looked closely at the brains of piglets to try to work out if permanent changes happen.
They looked at receptors on the surface of these cells whose job it is to grab passing blood sugar molecules for the cell to use as fuel.
After using injections of the hormone insulin to give the piglets a hypoglycaemic attack lasting two hours, brain cell samples were taken and the activity of these receptors compared with some taken from normal, healthy piglets.
Learning affected
They found that the receptors behaved differently in the previously blood sugar deprived brain cells, binding on to more sugar molecules.
This suggests that the attack may have caused long-term changes to the operation of the brain cells.
Lead researcher Jane McGowan said: "While some researchers question whether hypoglycaemia in infants has long-term detrimental health effects on the brain, we believe it does.
"Both learning and memory may be affected by any alteration of the ability of the brain to make synapses."
Deficits
British expert Professor Ann Burchell, from the University of Dundee, said that the evidence linking severe hypoglycaemic episodes with developmental deficits was strong.
However, she said that more money now needed to be spent working out how to spot the children most at risk of falling prey to blood sugar problems.
She told BBC News Online: "This area is woefully under-researched. The problem is that while hypoglycaemia in adults is easier to detect - you pass out, in babies, it can be asymptomatic.
"We need to be able to spot the babies which are at risk, then focus our resources on helping them."