According to a new report, exposure early in life to cow's milk may increase the lifetime risk of developing type 1 diabetes in some children.

• Dr. Johanna Paronen from University of Helsinki, Finland, and colleagues studied infants considered to be at high risk, since they had relatives with the disease.

• The children were fed either a regular cow's milk-based formula or a hydrolyzed casein-based formula after breast-feeding until the age of 6 to 8 months.

• At 3 months of age, infants fed cow's milk formula had a significantly higher immune response to cow insulin than infants who received the other formula or were breast-fed. No differences in reactivity were seen between the groups to human insulin.

Exposure to cow's milk has previously been shown to cause the body to mount an immune response to insulin in some children, but the link has been disputed.

Type 1 diabetes can be characterized by an "autoimmune" response, where the body's immune system attacks the pancreatic cells that produce insulin.

"Our observations raise the issue of whether oral exposure to foreign insulin plays a role in the autoimmune process leading to type 1 diabetes," Paronen and colleagues write. It could be that in some predisposed children, early exposure to cow's milk could trigger an immune reaction to insulin, they conclude.

Diabetes October, 2000;49:1657-1665.