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Does infant formula affect development of type 1 diabetes?

The study’s results don’t suggest any changes in guidelines for formula feeding to prevent type 1 diabetes. Purestock/Thinkstock

Diabetes is a disease in which the body has trouble making or using blood glucose, a sugar your body uses as fuel. Normally, when blood glucose levels rise, beta cells in the islets of the pancreas make and secrete the hormone insulin. Insulin triggers cells to take up sugar from the blood.

In type 1 diabetes, the body’s own immune system attacks and destroys the beta cells that make insulin. People with type 1 diabetes require lifelong treatment that involves frequent measurement of blood glucose and doses of insulin.

Some studies suggested that, in infants who are genetically susceptible, early exposure to complex foreign proteins, like those in cow’s milk, may increase the risk for an immune system reaction to beta cells and development of type 1 diabetes. An international group of researchers tested this idea in a study of infants in 15 countries. They enrolled more than 2,000 infants with a known genetic susceptibility to type 1 diabetes (in the gene for human leukocyte antigen, or HLA) and a close relative with the disease. The study was funded in part by NIH’s Eunice Kennedy Shriver National Institute of Child Health and Development (NICHD) and National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

The infants were randomly assigned to receive either a cow’s milk formula or an extensively hydrolyzed formula, in which the complex milk proteins have been broken down into small pieces. By the time they were eight months old, all the infants had taken their assigned formula for at least 60 days. The research team, which was led by Dr. Mikael Knip at the University of Helsinki, Finland, followed up with the infants until they were at least 10 years old. Results were published on January 2, 2018, in the Journal of the American Medical Association.

The researchers found that weaning with the hydrolyzed formula did not significantly decrease the incidence of type 1 diabetes compared to conventional formula after a median of 11.5 years (8.4% vs 7.6%). The groups didn’t differ even after the researchers adjusted for other factors, such as duration of breastfeeding, duration of formula feeding, sex, and region. Adverse effects also differed little between the groups.

“After more than 15 years of effort, this study puts to rest the controversy regarding the potential role of cow’s milk formula in the development of type 1 diabetes,” says Dr. Dorothy Becker at the University of Pittsburgh School of Medicine, who led the study in the United States. “This once more shows us that there is no easy way to prevent type 1 diabetes. Accordingly, there is no evidence to revise the current dietary recommendations for infants at high risk for type 1 diabetes.”

Becker adds that researchers continue to investigate ways to prevent diabetes.

—by Harrison Wein, Ph.D.