Pumping Iron Can Cut Your Diabetes Risk

By ALEXANDRA SIFFERLIN | August 7, 2012 | ANDERSEN ROSS / GETTY IMAGES

Two new studies published in the Archives of Internal Medicine underscore the benefits of exercise in preventing Type 2 diabetes and reducing the risk of death in people who already have the disease.

The first study, co-authored by Dr. Frank Hu, a professor of nutrition and epidemiology at the Harvard School of Public Medicine, looked at the risk of Type 2 diabetes in men who either exercised — aerobic activity, weight lifting or both — or were sedentary. The study included about 32,000 men, who were observed every two years for 18 years as part of the Health Professionals Follow-Up Study. Over that time, 2,278 men developed diabetes.

The researchers found that those who exercised had the lowest risk. Men who weight trained for a half-hour a day (2.5 hours a week) had a 34% lower risk of Type 2 diabetes than men who never hit the weight room. Those who combined weight lifting with a half-hour of aerobic activity each day — exercise including brisk walking and running — cut their risk by 59%, compared with sedentary men.

Research has long shown a link between aerobic exercise and lower risk of diabetes, but this is the first large study to look at the benefits of weight training independently, the authors say.

Even men who worked out less than 2.5 hours a week saw decreases in their diabetes risk: those who spent up to 59 minutes weight lifting each week reduced their risk by 12%, and those who lifted for 60 to 149 minutes per week had a 25% decreased risk, compared with men who didn’t weight train.

The government recommends a minimum 150 minutes of moderate-intensity aerobic exercise each week, plus two or more days a week of muscle-strengthening activities. Men who followed these recommendations had the greatest reduction in Type 2 diabetes risk, the authors say.

“We found that weight training is beneficial for diabetes independent of aerobic exercise. Each of them have independent effects, but the combination of both is most beneficial,” says Dr. Hu. “If someone doesn’t want to do aerobic exercise for various reasons, weight training can be an alternative.”

Increasing muscle mass by weight training helps boost the body’s metabolism, reduce insulin resistance and improve blood-sugar control. Combining weight training with the fat-busting benefits of aerobic exercise is the ideal recipe to ward off diabetes, says Hu.

The second study published in the Archives looked at men who were already diagnosed with Type 2 diabetes, and found that even low-impact physical activity can extend their lives. The study, by researchers at the German Institute of Human Nutrition in Nuthetal, included data on 5,859 men with diabetes who were part of a large ongoing prospective European study on nutrition and cancer risk; the study also included a meta-analysis of 12 previous studies on the link between physical activity and the risk of death from heart disease or any cause.

The data showed that men with diabetes can benefit significantly from regular exercise. Those who exercised moderately had a lower risk of death, compared with their couch potato counterparts. Men who spent the most time exercising in general — including low-impact exercise like walking and leisure-time physical activity like cycling, gardening and doing housework — had better odds of reducing their risk of death.

Results from prospective study suggest that moderately active men with diabetes are 38% less likely to die of any cause and 49% less likely to die of heart disease than inactive men. The meta-analysis showed that men who engaged in the most physical activity overall had a 40% lower risk of death than their sedentary counterparts.

“Everyone understands that they should exercise more,” says Mitchell Katz, director of the Los Angeles County Department of Health Services, who wrote an editorial accompanying the two new studies in the journal. “The million-dollar question is how to get people to exercise more. The question is can people structure their lives to get more exercise?

“People always think of it as an individual responsibility. As a diabetic you need to eat right and exercise more, but it ignores the fact that modern society in developed countries has evolved to the point that daily life provides no exercise.”

Katz says that larger changes, including urban restructuring to provide more bike and walking paths, for example, are needed to provide people with the opportunity to get their exercise in every day. “Fifty years ago people didn’t have cars. They got their fitness in their daily life. It’s not like that anymore and societal changes need to happen,” he says.

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