Woman at high risk of developing type 2 diabetes can increase their chances of staying healthy through exercise, according to a new study.
Researchers from Glasgow University found that insulin resistance in "high risk" women dropped by 22% after seven weeks of an exercise programme.
Insulin resistance is considered to be the most important biological risk factor for developing diabetes.
The British Heart Foundation (BHF) study will be published on Wednesday.
Dr Jason Gill, who heads the team that carried out the study, said: "The offspring of people with type 2 diabetes are about three times more likely to develop the disease than those with no family history of the disease.
"Not only is type 2 diabetes a very serious condition itself, but it can double or triple the risk of heart disease.
"In fact, more than two thirds of all people with diabetes will die from heart disease."
Dr Gill's team studied women between the age of 20 and 45 who usually did less than one hour of physical activity per week and had a sedentary job.
They tested 34 volunteers who had at least one type 2 diabetic parent against 36 volunteers whose parents had no history of the condition.
At the outset of the study the offspring of diabetics had higher insulin resistance than the controls.
All the women undertook an exercise training programme of three 30 minute exercise sessions in the first week, working up to five 60 minute sessions in weeks six and seven.
Exercise was focused on cardiovascular activities such as running, using a rowing machine, aerobics and cycling.
Dr Nick Barwell, who led the study, said: "The same exercise programme reduced insulin resistance to a vastly greater extent in the women with diabetic parents, telling us that exercise is particularly good at reducing diabetes risk in this vulnerable group.
"Our research shows that developing diabetes is not inevitable for people with a family history of diabetes.
"People at high risk have it within their power to substantially reduce their risk by increasing their activity levels."
Professor Peter Weissberg, medical director at the BHF, which funded the study, said: "We know that exercise is good for you, but seeing in black and white that this high risk group improved their own bodies' insulin resistance in just a couple of months is a striking demonstration of how effective it can be."
The research team said additional studies were needed to determine whether the benefits of exercise were also seen in men with diabetic parents.