It tested the effects of adding whey to a meal with a high glycaemic index (GI), meaning that it the carbohydrates are likely to be rapidly broken down, releasing sugar in a spike rather than gradual rate.
Whey proteins have already been demonstrated to reduce blood sugar response to meals in healthy subjects. This effect forms the basis of DSM's PeptoPro casein that is said to stimulate insulin release in the body, allowing glucose to be absorbed faster from the blood into the muscle cells and improving performance in athletes.
When the diabetic subjects took a whey supplement at the same time as a high GI breakfast or lunch, they too had lower blood sugar response and higher insulin response, report the researchers in this month's issue of the American Journal of Clinical Nutrition (vol 82, no 1, 69-75).
The findings suggest that whey supplements could help diabetics improve their blood sugar control.
The incidence of type 2 diabetes, accounting for 90 per cent of all diabetes, is rising fast around the world as a result of increasing obesity, bolstering the need to find ways of preventing and controlling the condition.
The World Health Organisation predicts that the number of people with type 2 diabetes will more than double over the next 25 years.
The mechanism for whey's action on insulin levels is not yet clear, although the team cited previous findings suggesting that certain amino acids and hormones in the milk protein seem to be involved.
The small study included 14 diet-treated subjects with type 2 diabetes. They were served a high-GI breakfast (white bread) and subsequent high-GI lunch (mashed potatoes with meatballs), which were supplemented with whey on one day and lean ham and lactose on another day.
The researchers took blood samples before and during four hours after breakfast and three hours after lunch.
The insulin responses were 31 per cent higher after breakfast and 57 per cent higher after lunch when whey was included in the meal than when whey was not included.
After lunch, the blood glucose response was significantly reduced after whey ingestion.
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," the team explains.
The authors are from University Hospital MAS in Malmö, Lund University and the University of Copenhagen in Denmark.