According to Canadian researchers any kind of exercise is better than none when it comes to controling type-2 diabetes.
They say exercise such as weight training works just as well as running on a treadmill or riding an exercise bike when it comes to the long-term control of blood sugar.
A combination of both aerobic and resistance training lowered blood sugar levels better than either alone, say the researchers and both are safe.
The World Health Organization says at least 194 million people worldwide have diabetes, and that figure is expected to rise to more than 300 million by the year 2025.
The majority of people have type-2 diabetes which is usually the result of a combination of factors such as genetic predisposition, lack of exercise and an unhealthy diet.
Experts believe that the type of exercise which raises the heart beat and makes people breathe a little heavily will reduce the risk of type-2 diabetes and improve the body's control of sugar.
But there have been some doubts about the safety and effectiveness of weight training.
In a study conducted by Dr. Ronald Sigal of Calgary University, Ottawa and his colleagues, 251 people with type-2 diabetes aged 39 to 70 who had never exercised regularly were assigned them to one of four groups.
One group did 45 minutes of aerobic training three times a week; another did the same amount of resistance training; another group did both, for a total of an hour and a half of exercise three days a week, while a fourth group did no extra exercise.
The exercisers used treadmills or exercise bikes, or weight machines, at a local health club and it was found that the volunteers liked the exercise and stayed with it.
Dr. Sigal says even among the medical profession there is widespread cynicism that people will follow an exercise programme.
They participants were given a diet to follow that should have prevented any weight loss, and then their blood sugar, cholesterol, weight and other vital statistics were measured.