Recent studies of the effects of vigorous exercise on glycemic control in patients with type 1 diabetes (formerly known as insulin-dependent diabetes mellitus, or IDDM) have yielded conflicting results. Most of these studies, however, have evaluated aerobic exercise only, not weight training. To study the effects of weight training combined with aerobic exercise, Mosher and associates evaluated the impact of 12 weeks of such a regimen on cardiovascular fitness, muscle strength, glucose control and lipid profiles in adolescent males with type 1 diabetes.

The study included 11 males with well-controlled type 1 diabetes and 10 males without diabetes. The mean age of the males with diabetes was 17.2 years; males without diabetes had a mean age of 19.4 years. Before beginning the exercise program, each participant's endurance, strength, body weight and composition were determined, as well as blood glucose, glycosylated hemoglobin and lipid levels.

The conditioning program consisted of 45 minutes of aerobic exercise and weight training three times a week for 12 weeks. The patients with diabetes consumed an evening meal supplemented by 5 to 10 g of complex carbohydrates two hours before their exercise sessions.

During the training sessions, only one patient with diabetes had a hypoglycemic episode. By the end of the 12-week training period, the patients with diabetes had gained lean body mass (3.5 percent) and decreased body fat by 5.2 percent. Cardiorespiratory endurance improved by 10.5 percent and 12.0 percent in the diabetes and control groups, respectively. Glycosylated hemoglobin levels in the group with diabetes fell by 0.96 percent, even though control was good before the study began. Total cholesterol levels decreased in the persons with diabetes, although not significantly. Both groups showed significantly increased high-density lipoprotein cholesterol levels and significantly decreased low-density lipoprotein cholesterol levels.

The authors conclude that the aerobic and weight training program improved muscle strength, cardiorespiratory endurance and lean body mass in the males with diabetes. It also led to improved lipid profiles and glycosylated hemoglobin levels in these patients, even though this group of adolescents had well-controlled type 1 diabetes. The improved cardiovascular fitness and endurance could reduce their risk of early coronary artery disease as well.