“We all know that aerobic exercise is beneficial for diabetes — many studies have looked at that — but no studies have looked at weight training,” said study leader Frank Hu, at the Harvard School of Public Health.

“This study suggests that weight training is important for diabetes, and probably as important as aerobic training.”

Hu and his colleagues, whose report was published in the Archives of Internal Medicine, used data on more than 32000 male health professionals, who answered questionnaires every two years from 1990 to 2008.

On average, four out of 1000 men developed type 2 diabetes every year, the researchers found.

The risk of getting the blood sugar disorder was only half as high for men who did cardio, or aerobic, workouts — say brisk walking, jogging or playing tennis — at least 150 minutes a week, as for those who didn’t do any cardio exercise.

Men who did weight training for 150 minutes or more had a risk reduction of a third compared to those who never lifted weights, independently of whether or not they did aerobic exercise.

Whereas weight training increases muscle mass and can reduce abdominal obesity, it tends not to cut overall body mass, said Hu.

The results don’t prove that working out staves off diabetes, because many men who stay fit may also be healthier in other ways, but the researchers did their best to account for such potential differences, including age, smoking and diet.

“I think the benefits of weight training are real,” said Hu.

“Any type of exercise is beneficial for diabetes prevention, but weight training can be incorporated with aerobic exercise to get the best results.”