For people with type 2 diabetes, adding whey to high-carbohydrate meals stimulates insulin release and reduces spikes in blood glucose levels after meals, according to new findings.

Writing in the American Journal of Clinical Nutrition, Dr. Mikael Nilsson, of Lund University, Sweden, and colleagues say the reason whey proteins have this effect is not known, but it may have something to do with particular amino acids and hormones found in the mild product.

The researchers examined the effect of supplementing high glycemic index (GI) meals -- that is, readily digested carbs that cause a rapid rise in blood sugar levels -- with whey proteins.

A total of 14 individuals with type 2 diabetes were served a high-GI breakfast (white bread) and subsequent high-GI lunch (mashed potatoes with meatballs). Whey supplementation was provided with both meals on one day, and whey was exchanged for lean ham and lactose on another day.

The investigators took blood samples before and during a 4-hour period after breakfast and 3 hours after lunch in order to measure blood glucose, insulin, and other factors.

Insulin secretion was higher after both breakfast and lunch when the meals were supplemented with whey compared to when whey was not included, although the effect was less pronounced after breakfast. The rise in blood glucose was significantly reduced after the lunch meal was supplemented with whey.

The lesser effect on insulin of whey after breakfast, "in combination with the fact that the insulin resistance may be higher in the morning after the overnight fast, may explain the inability of whey to reduce the blood glucose increment after breakfast," Nilsson's team explains.

SOURCE: American Journal of Clinical Nutrition, July 2005.