We do now.
Until now all the published studies on exercise for people with type 2 diabetes have been small ones. No large studies with enough statistical power existed.
Most studies looked at diet and exercise or medication and exercise together. Only 14 small randomized controlled trials from nine different countries with a total of 377 participants looked at the effects of exercise alone.
A new systematic review of these studies together gives us results that are both statistically and clinically significant. Exercise significantly increases insulin response, decreases triglycerides, and helps us to burn body fat.
Perhaps most significant is that exercise reduced A1C by 0.6 percent. Doesn’t sound like a lot? Consider that for someone with an A1C of 9 percent, this is a 30 percent improvement toward the American Diabetes Association’s general target of 7 percent and a 20 percent improvement toward a normal value of 6 percent.
This significant reduction in A1C came quickly. The 0.6 percent drop came in studies that typically took either eight or 16 weeks. The two longest studies were 24 and 52 weeks.
The Cochrane Database of Systematic Reviews just published the review July 19. Only an abstract is free online, but two of the authors kindly sent me a PDF of their 40-page analysis.
No publication has higher standards than Cochrane. The Cochrane Collaboration is an international not-for-profit organization that provides up-to-date information about the effects of health care.
The authors of the new review are all Australian. Diana Thomas, M.D., is the scientific director at the Centre for Evidence Based Paediatrics Gastroenterology and Nutrition, Children’s Hospital at Westmead near Sydney. Elizabeth Elliott, M.D., is the director of that center. And Geraldine Naughton, Ph.D., is associate professor in paediatric exercise science at Australian Catholic University at Strathfield, also near Sydney.
Drs. Thomas and Naughton independently picked the appropriate studies and at first found 2,101 of them. But only 14 studies were relevant. The biggest share of the others didn’t look at the effects of exercise alone.
The studies in this systematic review included several types of exercise, both aerobic – brisk walking, cycling, swimming, and jogging – and resistance training – like exercise with free weights or weight machines. Most of the studies involved three exercise sessions per week on non-consecutive days. “This accords with recovery and adaptation principles of exercise programming,” the review states.
The duration of exercise in the 14 studies varied considerably. Two studies of resistance training were for 30 minutes a day. A Qi Gong program was 120 minutes. Seven of the studies were of hour-long programs.
One of the conclusions that I especially liked is that easy exercise is best. “The easier the exercise is to maintain, the more likely that people will do it,” they wrote. “Therefore, mild to moderate exercise performed regularly will be of more benefit than short bursts of high intensity exercise, which would be difficult to maintain over long periods.” Still, most of us who prefer to get our exercise walking do need to walk faster.
Variety is the other key to a successful exercise program. The authors recommend that we do several types of exercises to avoid the monotony of a single exercise program.
I stick with my one favorite exercise – hiking. But I avoid boredom by hiking different trails all the time.
Anecdotally, we have known for a long time that we can control our diabetes a lot better with exercise. “Our study gives justification to the recommendation that exercise is important,” Dr. Elliott said.
All of us probably know that when we exercise we feel better. It usually feels like work when we are working out, but that just makes the rest of the day – and all the days of our life – feel that much better. Time to hit the trail.