Exercise and diet can dramatically lower the risk of developing type 2 diabetes, scientists claim this week. This conclusion was reached on completion of the first major clinical trial in the US to compare the effects of diet and exercise versus medication in the prevention of type 2 diabetes, ReutersHealth reports. The trial, sponsored by the National Institutes of Health (NIH), found that at-risk people who exercised at least 30 minutes a day reduced their risk by 58 per cent, even without medication. In contrast, those who used the diabetes drug Glucophage (metformin) without diet and exercise reduced the risk by only 31 per cent. Type 2 diabetes is strongly associated with obesity. "In view of the rapidly rising rates of obesity and diabetes in America, this good news couldn't have come at a better time," said Department of Health and Human Services (HHS) Secretary Tommy Thompson. The findings come from the Diabetes Prevention Program (DPP), a large-scale clinical trial conducted at 27 centres nationwide and involving more than 3,000 participants. Participants ranged in age from 25 to 85, and were required to sustain a 5 per cent weight loss over the study's 3-year duration. Lead researcher Dr. David Nathan urged that more research was required to provide further evidence that diet and exercise can reduce type 2 diabetes risk. "We simply don't know how long, beyond the 3-year period studied, diabetes can be delayed," he explained. An estimated 16 million Americans have type 2 diabetes, according to the Centers for Disease Control and Prevention (CDC). Type 2 diabetes is also a major cause of kidney failure, limb amputations and blindness in adults, according to CDC figures.