What may be best for controlling diabetics’ blood sugar? Sustained, structured exercise

Exercise is beneficial for diabetics, but some questions remain -- how much exercise is needed, and what kind? A study finds that structured exercise programs lasting 150 minutes or more a week may be best for those with type 2 diabetes.

The meta-analysis released Tuesday in the Journal of the American Medical Assn. examined 47 randomized clinical trials that included 8,538 patients and lasted at least 12 weeks. Of those studies, 23 focused on structured exercise training and 24 looked at physical activity advice, and all assessed how much the programs lowered hemoglobin A1c levels, a test used to evaluate blood sugar control over several months.

In general, structured exercise programs were linked with an HbA1c drop of 0.67% compared with those in control groups. When researchers broke those programs down, structured aerobic programs lowered the levels 0.73%, structured resistance training brought them down 0.57%, and the two combined dropped levels 0.51%. Structured exercise was defined as planned and supervised exercise that was tailored to the individual.

When exercise time was examined in the studies, researchers determined that structured exercise lasting more than 150 minutes per week was linked with an HbA1c decline of 0.89%. Going below that resulted in a decline of only 0.36%. Exercising a minimum of 150 minutes a week (usually broken down to 30 minutes of exercise five days a week) is recommended by such institutions as the American College of Sports Medicine.

When advice on physical activity and diet were combined, HcA1c levels dropped 0.58% compared with controls, but receiving advice on physical activity alone wasn’t associated with any changes in levels.