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Diet Beats Drugs for Diabetes Prevention

Study Shows Lifestyle Changes Are More Effective Than Drugs in Preventing Diabetes

By Salynn Boyles
WebMD Health News

Reviewed by Brunilda Nazario, MD

Oct. 28, 2009 -- Lifestyle changes resulting in long-term weight loss of just a few pounds proved to be roughly twice as effective as drug treatment for preventing type 2 diabetes in an ongoing government-sponsored trial.

Researchers followed almost 3,000 high-risk patients for a decade in one of the largest and longest studies aimed at preventing diabetes ever conducted in the U.S.

Roughly a third of the participants were initially asked to eat a low-fat diet and engage in at least 30 minutes of moderate activity a minimum of five times a week, with the goal of losing 7% of their body weight within a year.

Another third were put on the diabetes drug metformin; the remaining patients initially received no intervention.

Many of the people in the lifestyle intervention group met the weight loss goal, losing an average of 15 pounds during the first year of the study.

While they regained, on average, 10 of those pounds during the next seven years, the lifestyle intervention group continued to have the lowest rates of diabetes.

"Weight loss is still the most important thing we have to recommend to overweight people at risk for type 2 diabetes," William C. Knowler, MD, of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), tells WebMD. "This study shows that the benefits of even modest weight loss can persist for many years."

Reduction in Diabetes Incidence

Three years into the trial, Knowler and colleagues reported that diabetes incidence was reduced by a whopping 58% in the lifestyle intervention group and 31% in the metformin group, compared to people who received no intervention.

This dramatic difference led the researchers to offer lifestyle intervention, in the form of group counseling and support sessions, to all three groups for the rest of the study.

The 10-year follow up analysis, which appears Thursday in TheLancet, shows that:

Compared to the non-intervention group, patients in the intensive lifestyle intervention group and metformin group, respectively, were 34% and 18% less likely to develop diabetes over 10 years.
Lifestyle intervention was found to delay the onset of diabetes by four years. Drug treatment delayed diabetes by two years.
The benefits of intensive lifestyle intervention were particularly strong in the elderly. Those aged 60 and older in the diet and exercise group lowered their rate of developing diabetes by half over 10 years.

"Lifestyle and metformin were both useful for delaying or preventing diabetes," says endocrinologist and co-researcher Ronald Goldberg, MD.

The researchers will continue to follow the study participants for at least another five years. One goal of the continued follow-up is to determine the impact of the lifestyle and drug interventions on the development of diabetes complications, such as nerve damage and blindness.

Diabetes on the Rise

About one in 10 adults in the U.S. -- roughly 24 million people -- have diabetes, and an additional 57 million are at risk for developing the disease because they are overweight or obese and have impaired blood sugar control.

Goldberg says the study findings highlight the importance of making prevention and lifestyle interventions a focus of national health care reform. He is professor of medicine in the division of endocrinology, diabetes, and metabolism at the Diabetes Research Institute, University of Miami Miller School of Medicine.

"The biggest expense in diabetes comes from treating the complications of disease," he says. "If we can show that these interventions keep people from developing these complications, this could have an enormous impact."