Developed by a panel of 9 experts, the new guidelines are published concurrently in the December issue of Medicine & Science in Sports & Exercise and Diabetes Care.
"High-quality studies establishing the importance of exercise and fitness in diabetes were lacking until recently," the expert panel writes, "but it is now well established that participation in regular physical activity improves blood glucose control and can prevent or delay type 2 diabetes mellitus, along with positively affecting lipids, blood pressure, cardiovascular events, mortality, and quality of life."
Most of the benefits of exercise are realized through acute and long-term improvements in insulin action, accomplished with both aerobic and resistance training, the experts write.
For people who already have type 2 diabetes, the new guidelines recommend at least 150 minutes per week of moderate to vigorous aerobic exercise spread out at least 3 days during the week, with no more than 2 consecutive days between bouts of aerobic activity. These recommendations take into account the needs of those whose diabetes may limit vigorous exercise.
"Most people with type 2 diabetes do not have sufficient aerobic capacity to undertake sustained vigorous activity for that weekly duration, and they may have orthopaedic or other health limitations," said writing chair Sheri R. Colberg, PhD, professor of exercise science at Old Dominion University and adjunct professor of internal medicine at Eastern Virginia Medical School, Norfolk, Virginia, in a statement. "For this reason, the ADA [American Diabetes Association] and ACSM [American College of Sports Medicine] call for a regimen of moderate-to-vigorous activity and make no recommendation for a lesser amount of vigorous activity."
The panel specifically recommends that such moderate exercise correspond to approximately 40% to 60% of maximal aerobic capacity and states that for most people with type 2 diabetes, brisk walking is a moderate-intensity exercise.
The expert panel also recommends that resistance training be part of the exercise regimen. This should be done at least twice a week — ideally 3 times a week — on nonconsecutive days. The panel also recommends that people just beginning to do weight training be supervised by a qualified exercise trainer "to ensure optimal benefits to blood glucose control, blood pressure, lipids, and cardiovascular risk and to minimize injury risk."
Regular use of a pedometer is also encouraged. In a meta-analysis of 8 randomized controlled trials and 18 observational studies, people who used pedometers increased their physical activity by 27% over baseline. Having a goal, such as taking 10,000 steps per day, was an important predictor of increased physical activity, according to the expert panel.
Finally, the new guidelines emphasise that exercise must be done regularly to have continued benefits and should include regular training of varying types.
Physicians should prescribe exercise, Dr. Colberg said in a statement. "Many physicians appear unwilling or cautious about prescribing exercise to individuals with type 2 diabetes for a variety of reasons, such as excessive body weight or the presence of health-related complications. However, the majority of people with type 2 diabetes can exercise safely, as long as certain precautions are taken. The presence of diabetes complications should not be used as an excuse to avoid participation in physical activity."
Dr. Colberg and the other authors have disclosed no relevant financial relationships.