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September 2001

Diabetes Study Shows Value In Diet, Exercise - Mary Ellen Butler

Tommy Thompson
Tommy Thompson
BETHESDA, MD.-Exercising as little as 30 minutes a day and eating a healthy diet can help delay or prevent the onset of Type 2 diabetes by more than 50 per cent for those at high risk for the disease, according to the results of a national prevention trial released at the beginning of August.

The results of the five-year study, funded by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), were deemed so convincing by the study's external data monitoring board that they ended the clinical trial this spring, a year ahead of schedule. This information comes at a time when public health officials are calling diabetes and its health consequences an "epidemic."

Sixteen million Americans already have diabetes, but more than 5 million of them are undiagnosed. Diabetes usually affects those over age 40 and is more likely to occur in those who are obese or in people with a family history of the disease.

"It couldn't come at a better time," said Health and Human Services secretary Tommy Thompson last month. "In the last 10 years, Type 2 diabetes has exploded. The population is aging; our most vulnerable ethnic populations are increasing as well. Americans weigh more than ever before and too many people live sedentary lives."

Study Targeted High Risk Groups
The Diabetes Prevention Program (DPP) compared diet and exercise to treatment with the drug metformin (or Glucophage) in 3,234 people with impaired glucose tolerance, a condition that puts people at high risk for diabetes.

Study participants were randomly assigned to either a lifestyle intervention group, treatment with metformin, or to receive a placebo. Participants in all three of the study arms were advised about healthy eating and exercise.

Those assigned to the lifestyle group reduced their diabetes risk by 58 per cent. On average, that group maintained their physical activity at 30 minutes per day and lost 5-7 per cent of their body weight, or 10-15 pounds. This segment of the study was especially successful for older participants, aged 60 and older, who reduced their development of diabetes by 71 per cent through lifestyle changes.

The study called for participants to lower their fat intake to less than 25 per cent of their caloric intake. Participants in this segment of the study received six months of instruction in healthy eating, exercise and behavior and less frequent follow up sessions over the next few years.

Participants in the metformin portion of the study received 850 mg twice a day of the drug and were able to reduce their risk of developing diabetes by 31 per cent. The drug therapy was most effective in the younger participants (ages 25-40) and those who had more substantial weight problems (50-80 pounds overweight).

About 29 per cent of the placebo group developed diabetes during the three-year follow-up period. However, in the lifestyle arm only 14 per cent developed the disease and in the drug arm of the study, 22 per cent developed diabetes. It is unclear if the interventions can completely prevent diabetes, but researchers plan to continue to follow the study participants to see how long the interventions are effective.

Smaller studies on diabetes prevention have been conducted in China and Finland with similar results. However, this large-scale trial with 27 sites across the country is the first to show that significant reductions can be made with a diverse American population.

The study was made up of people who were at high risk for developing diabetes. All of the participants had impaired glucose tolerance, as measured by an oral glucose tolerance test and all were overweight. In addition, about 45 per cent of the study participants were minorities (African Americans, Hispanic Americans, Asian Americans and Pacific Islanders, and American Indians) and therefore at a greater risk. Other high-risk groups included in the study were people age 60 and older, women with a history of gestational diabetes, and people with a family history of Type 2 diabetes.

Study Message Is Clear
Although the study focused only on people at high-risk for diabetes, many researchers think the interventions could be applied on a wider scale. That is one of the areas that will be considered as policy makers formulate recommendations for physicians and patients this fall.

Thompson announced last month that HHS will create a task force to translate the results of the DPP study. The recommendations will be due at the end of the year. Once the recommendations are ready, Thompson said HHS staff would lead by example by increasing their own exercise and going on a diet. He urged other government departments, private companies and groups to follow the department's lead.

With the clear success of weight loss and exercise in the DPP study, physicians will have solid proof to give to high-risk patients, said Dr. Steven Kahn, the principle investigator at the DPP's Seattle site within the Department of Veterans Affairs Puget Sound Health Care System. Dr. Kahn, research director at the Puget Sound VA system and a professor of medicine at the University of Washington, said that not only is the message clear to patients, but it will be easy for physicians to dispense this advice because the lifestyle interventions were effective across the board, for all ages and ethnic groups.

Looking Ahead
In addition to continuing to follow up with the DPP participants, some similar work will be carried out over the next several years in patients who have already developed diabetes. A new study launched this summer, called Look AHEAD (Action for Health in Diabetes), will examine the long-term effects of weight loss in men and women who are overweight and have Type 2 diabetes.

The clinical trial will look specifically at the long-term effects of weight loss on health, especially heart attack and stroke. This project is also being funded by NIDDK. More information is available about the trial at www.lookaheadstudy.org .

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