WEDNESDAY, Oct. 28 (HealthDay News) -- Diet and exercise can keep diabetes at bay for a decade, cutting the risk for the disease by more than a third in the most susceptible people, a new study finds.

About 11 percent of U.S. adults (24 million) have diabetes, mostly type 2, which is linked to poor diet and sedentary lifestyle. In addition, 57 million overweight adults have higher-than-normal blood sugar levels, which raise the risk of a heart attack or stroke and the likelihood of developing type 2 diabetes, researchers say.

But new research, published in the Oct. 29 online edition of The Lancet, shows that losing weight and exercising can delay or prevent the onset of diabetes more effectively than the prescription drug metformin or a placebo.

"Interventions that result in weight loss lower the risk of diabetes, and that lower risk appears to persist for a long period of time," said study author Dr. William C. Knowler of the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.

For people who are at high risk of getting diabetes, losing weight "is clearly to be recommended," he said. In addition, using a drug like metformin may also benefit people unable to lose weight through exercise and diet alone, he said.

For the diabetes prevention study, 3,234 overweight or obese adults with elevated blood sugar levels were randomly assigned to either lifestyle changes or metformin to control their blood sugar, or a placebo.

After 10 years, 2,766 remained in the trial, and those taking metformin saw an 18 percent reduction in their rate of developing diabetes, compared with those on placebo.

But those who had made lifestyle changes -- reducing caloric and fat intake and exercising at least 150 minutes a week -- reduced their risk of getting diabetes by 34 percent compared with those on placebo, the researchers found.

In the first year of the trial, people in the lifestyle group lost an average of 15 pounds, regaining all but about five pounds over 10 years. People on metformin maintained a five-pound weight loss, and those on placebo lost less than two pounds over 10 years, the researchers note.

Over 10 years, after all the participants made lifestyle changes, the yearly diabetes incidence rates for the drug and placebo groups had dropped to about 5 to 6 percent, the same rate as the lifestyle group.

"Lifestyle intervention, even when provided later, also seemed to lower diabetes incidence rate," Knowler said.

But losing weight is difficult, and simply telling someone to slim down won't work, he acknowledges.

"To make things like this happen on a large scale, we have to do more than simply tell people to lose weight," he said. People need access to weight loss clinics that can teach them about diet and exercise, he added.

Dr. Anoop Misra, director of the department of diabetes and metabolic diseases at Fortis Hospitals in India, and author of an accompanying journal editorial, said that "prevention of diabetes is important to curb epidemic of diabetes globally. Diet and exercise remain the most important modalities to prevent diabetes, and any drugs are less important."

At-risk groups of diabetes need to be identified, especially certain ethnic groups, and taught proper lifestyle management strategies, Misra said. "Young adults with family history of diabetes should be carefully managed along the same lines," he said.

Diabetes prevention makes economic sense as well, by decreasing costly, lifelong expenditures on management of the disease and its complications, Misra said.

All nations, particularly developing countries, seeing a rapid rise in diabetes should devise or strengthen a national diabetes-control program to help curb the epidemic, he said.

"In particular, regulations should apply for advertisement and sale of energy-dense junk food to children, and regular physical activity should be encouraged starting at a young age. Spreading awareness about proper lifestyle and adverse consequences of obesity and diabetes should be at the top of health agenda of all nations," Misra said.

Regarding the study findings, other experts are optimistic. Dr. Ronald Goldberg, a professor of medicine at the Diabetes Research Institute of the University of Miami Miller School of Medicine, whose institution participated in the study, said that "seeing quite significant effects lasting this long really bodes well for the utility of these interventions for diabetes prevention."

Cutting calories and increasing physical activity clearly slow the progression to diabetes, Goldberg said. "Lifestyle works, and every effort needs to be made to begin and maintain a lifestyle program in the long-term."

More information

For more information on diabetes, visit the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.

SOURCES: William C. Knowler, M.D., Ph.D., M.P.H., U.S. National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, Ariz; Anoop Misra, M.D., director and head, department of diabetes and metabolic diseases, Fortis Group of Hospitals, New Delhi and NOIDA, India; Ronald Goldberg, M.D., professor of medicine, Diabetes Research Institute, University of Miami Miller School of Medicine; Oct. 29, 2009, The Lancet, online

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