Weight training alone or with aerobic exercise may lower diabetes risk in men, Harvard University research showed, while a German study found that physical activity keeps those with the disease alive longer.
Lifting weights 30 minutes a day, five times a week, may reduce a man's chance of developing Type 2 diabetes by as much as 34 percent, and when combined with aerobic exercise like brisk walking or running, cuts the risk as much as 59 percent, according to the Harvard research posted online in the Archives of Internal Medicine. The German study showed that people with diabetes who were moderately active had a 38 percent lower risk of dying compared with those who didn't exercise.
The Harvard study is the largest on the benefits of weight training and aerobic activity on diabetes, while the German research is the biggest to look at exercise and mortality in diabetics, the authors said. More studies are needed to find better ways to motivate people to exercise, said Mitchell Katz, director of the Los Angeles County Department of Health Services, who wrote an accompanying editorial in the journal.
"How to increase motivation to stay active is the $1 million question facing physicians and health care experts and not just because of diabetes," Katz said in an email. "A number of diseases including cardiac disease, the most common cause of death in the U.S., and cancer, the second-most common," are reduced through exercise, he said.
About 346 million people worldwide have Type 2 diabetes, and diabetes-related deaths may double between 2005 and 2030, according to the World Health Organization.
In the study from the Harvard School of Public Health and the University of Southern Denmark, the researchers looked at 32,002 men from the Health Professionals Follow-up Study from 1990 to 2008. During that time 2,278 men developed diabetes.
Men who did weight training one to 59 minutes a week reduced their diabetes risk by 12 percent, those who engaged in weight training 60 to 149 minutes a week reduced their risk by 25 percent and those who weight trained for at least 150 minutes a week lowered it by 34 percent compared with those who did no weight training, the authors said. Combining 150 minutes a week of weight training with 150 minutes of aerobic exercise reduced diabetes risk by 59 percent.
"When we use our muscles as in weight training our body's insulin resistance goes down, meaning we more readily move blood sugar from the bloodstream into the cells and we require less insulin to do that so that the blood sugar levels stay lower and put less demand on the pancreas to produce insulin," said Walter Willett, the author of the first study and chair of the Department of Nutrition at the Harvard School of Public Health in Boston.
"The more we paint the full picture of the consequences of staying on the couch, the more people we are likely to motivate to put some activity into their lives," Willett said in a telephone interview. "This is looking at one part of the picture -- diabetes -- but more importantly to people, even a few minutes a day of strength training can make an important difference. There are immediate benefits of feeling better."
The second study, led by researchers from the German Institute of Human Nutrition in Nuthetal, looked prospectively at 5,859 patients with diabetes and found that those who engaged in moderate amounts of exercise were at a lower risk of death compared with those who were inactive. In an analysis of 12 studies, the researchers found that higher levels of total physical activity, leisure-time physical activity and walking were related to a lower risk of overall mortality and death from heart diseases.
"Compared with being inactive, being moderately active may already improve survival in persons with diabetes," said Diewertje Sluik, the lead study author and a doctor of public health with the nutrition institute, in an email. "Unfortunately, not many diabetes patients engage in regular physical activity. Therefore, it is necessary to promote active lifestyles among persons with diabetes and future research should determine why persons do not adhere to this advice."