Exercise Combination Cuts Blood Sugar in Type 2 Diabetics

WASHINGTON—Combining aerobic exercise and resistance training lowered blood-sugar levels in people with Type 2 diabetes, a new study has found.

The same improvement in glycemic levels wasn't seen among patients who performed aerobic exercise or resistance training alone, according to the study, which will be published in this week's Journal of the American Medical Association.

Patients who walked and lifted weights also lost more fat and trimmed their waistlines more than people who did just one type of exercise even though the time devoted to exercising was similar—findings researchers said apply to everyone.

Although it's accepted that regular exercise provides big benefits for people with Type 2 diabetes and helps many reduce the use of diabetes medications, the exact exercise type has been unclear.

Type 2 diabetes is characterized by high blood-glucose levels caused by the body's inability to either make or properly use insulin and is often associated with older age and weight gain. (Type 1 diabetes is an autoimmune disease often diagnosed in children in which the body's immune system destroys pancreatic beta cells that produce insulin.)

The study's lead researcher, Timothy S. Church, a doctor and exercise researcher at the Pennington Biomedical Research Center, Louisiana State University System in Baton Rouge, explained that the combination of resistance training and aerobics works muscles in different ways and provides more benefit than doing each type of exercise alone. Muscles consume sugar and stronger muscles leave less sugar in the blood, which is of particular benefit to people with diabetes.

"I think our results apply to everybody personally," Dr. Church said. "Muscle is happiest when you do aerobic exercise and resistance."

The study involved 262 sedentary people with Type 2 diabetes to look at whether a nine-month exercise program had an impact on A1C blood hemoglobin levels, a common measurement of blood glucose, or blood sugar. A1C measures the average blood sugar over about three months.

About 73 people each were assigned to one of three exercise groups while a fourth group of about 40 patients were non-exercisers and used as a comparison group.

One group walked on a treadmill for a total of 150 minutes a week, and another group lifted weights three times a week. The exercises consisted of two sets of nine exercises targeting the upper body, abdomen and legs. Each set consisted of 10 to 12 repetitions.

The third exercise group walked for about 110 minutes a week and lifted weights twice a week by doing one set of nine exercises. The three groups were designed to expend about the same amount of energy.

All of the exercise was supervised, and the weight training involved the use of machines. Patients in the study were about 56 years old on average, overweight and were considered sedentary upon study entry. The average hemoglobin A1C was 7.7%.

After nine months, the absolute change in hemoglobin A1C for the combination exercise compared to the non-exercise group was a statistically significant drop of 0.34%. Such declines in A1C reduce the risk for diabetes complications including cardiovascular disease, kidney disease, nerve and eye damage.

While those in the aerobic-exercise group and those in the resistance training, or weight-lifting group, had small declines in hemoglobin A1C compared to non-exercisers, the changes were not considered statistically significant.

Dr. Church noted that the changes in A1C were seen despite increases in the use of diabetes medications meant to control blood sugar among patients in the non-exercise group and decreases in medication among those in the exercise groups.

Although study participants lifted weights in a gym, Dr. Church said, resistance training can be done outside of a gym with free weights, resistance bands or tubing and using one's own body to do things like abdominal crunches and push-ups.

The study was funded by the National Institutes of Health. Dr. Church has overseen other studies funded by pharmaceutical firms, including Sanofi Aventis SA and Amylin Pharmaceuticals Inc.