Premature infants who were given a diet rich in nutrients had significantly higher levels of fasting proinsulin than infants who ate a less-nutritious diet, British researchers report in the March 28 issue of The Lancet.
Proinsulin is a substance believed to be a marker for insulin resistance and the possible development of Type 2 diabetes, the researchers say.
"We have found that infants born prematurely who grew fastest in the first two weeks of life had higher proinsulin levels in adolescence than those who had the slowest growth," says the study's lead author, Dr. Atul Singhal. He is deputy director of the MRC Childhood Nutrition Research Center at the Institute of Child Health in London.
"Faster growth during a crucial window after birth may increase later risk factors for diabetes and cardiovascular disease," Singhal says.
The researchers took blood samples from 216 teens between the ages of 13 and 16 years who had been born prematurely and had participated in infant nutrition studies. They also took blood samples from 61 healthy teens who had been born at full-term for comparison.
The premature infants had been fed either a low-nutrient diet (breast milk or standard infant formula) or an enriched diet (a special formula for pre-term infants) when they were born in the 1980s. Pre-term formula is fortified with protein, fat, vitamins and minerals. At that time, the effects of diet on premature infant growth had not been well studied.
In the study, the teens' blood samples were tested for levels of blood sugar, insulin and several types of proinsulin.
The only significant difference between the groups was in a test of a type of proinsulin known as 32-33 split proinsulin, which Singhal says can be a marker for the development of non-insulin dependent -- or Type 2 -- diabetes. Levels of this type of proinsulin were 20 percent lower in the youngsters who had been fed a lower nutrient diet in the first few weeks of life.
"So, our study suggests that overfeeding after birth that promotes too rapid growth should be avoided," says Singhal.
"Because it is difficult to overfeed breastfed babies in the first few weeks, our study is another piece of evidence that breastfeeding is the best way to feed young babies," he adds.
However, the study results definitely do not mean that parents should restrict what their baby eats, cautions Singhal.
He recommends talking with your health-care provider "to ensure that your child grows at a steady but not excessive rate, particularly if bottle-feeding."
Dr. Denise Blumberg is director of pediatric endocrinology at Nassau University Medical Center in East Meadow, N.Y. She says, "This study raises the question of what effect nutrition levels in early infancy have on long-term health. It's interesting, but needs further study."
"No one should change what they're doing for premature infants at this point," she says.
Blumberg adds that "undernutrition" can cause problems in early growth and development in infants. And, she points out, formula and medical interventions for premature infants have changed significantly since the 1980s when the children in the study were born. So, tests done on children born today might have different results.
Additionally, Blumberg says high levels of split 32-33 proinsulin aren't a routine measure of who will develop diabetes or insulin resistance. She also notes that many factors throughout life affect the development of diabetes, including diet, exercise, stress levels and exposure to infection.