More Evidence That Exercise Improves Glycemic Control

Either aerobic or resistance training alone improves glycemic control in type 2 diabetes, but the improvements are greatest with combined aerobic and resistance training.

 Previous studies have demonstrated benefits of single types of exercise on glycemic control for diabetics. These Canadian investigators compared aerobic training alone, resistance training alone, and both types of exercise with a sedentary control group. Exercise sessions were held 3 times weekly for 22 weeks. Participants had to be compliant with the training program for 4 weeks prior to enrollment to be included. Aerobic sessions worked up to 45 minute duration at target heart rate of 75% of estimated maximum. Resistance training was done on 7 different machines with specified numbers of repetitions and weight progression. A limitation to this study is that participants were not blinded.

A total of 251 participants were enrolled. Baseline HbA1c was had a mean between 7.4 and 7.5 in each of the groups. HbA1c at 6 months was a mean of 6.56 in the combined training group, 6.98 in the aerobic training group, 7.18 in the resistance training group, and 7.51 in the sedentary group. Changes at 6 months in blood pressure and lipids did not differ statistically between groups. The combined training group spent more time exercising, so it is not clear whether it was total exercise time or type of training that made the difference.

The authors concluded: “Either aerobic or resistance training alone improves glycemic control in type 2 diabetes, but the improvements are greatest with combined aerobic and resistance training.” Bottom line is that exercise is good, more is better. Ann Intern Med 18 September 2007, 147:357-369