(Bloomberg) — Diet and exercise remain the best bet for staving off diabetes in patients at risk for the disease, according to a 15-year follow up on a landmark study that set lifestyle intervention as an effective approach.

Study participants who lost weight and increased physical activity had a 27 percent lower rate of developing Type 2 diabetes, compared with 17 percent of those given metformin, a first-line drug to lower blood sugar. The research was reported today at the American Diabetes Association meeting in San Francisco.

More than 29 million people in the U.S. have diabetes, according to the Centers for Disease Control and Prevention. Another 86 million are estimated to have prediabetes, in which blood sugar is higher than normal, though not enough to be classified as full-blown diabetes. People with prediabetes are at risk for the disease without adopting a healthier lifestyle.

“Diabetes is a disease that really develops across decades,” Judy Fradkin, of the National Institute of Diabetes and Digestive and Kidney Diseases, said in a press briefing. “Although rates of diabetes have been increasing dramatically, outcomes for people with and at risk of diabetes have been improving dramatically.”

Diabetes, which results when the body doesn’t use insulin properly or doesn’t make the hormone, is the seventh-leading cause of death in the U.S. Insulin is a hormone secreted by the pancreas that helps the body control blood sugar. Type 2, in which the body doesn’t use insulin properly, accounts for about 95 percent of diabetics.

 

Diabetes Prevention

 

The Diabetes Prevention Program began in 1996 and enrolled more than 3,000 people in the U.S. who had prediabetes. The three-year study compared intensive lifestyle counseling, with metformin and a placebo group. Today’s study, called the Diabetes Prevention Program Outcomes Study, began in 2003 and included about 2,700 people from the original trial, all of whom were offered lifestyle intervention, said David Nathan, chairman of both studies and a professor of medicine at Harvard Medical School in Boston.

The findings also showed that patients without diabetes had a 28 percent lower occurrence of related complications, such as damage to eye, nerves and kidneys, than those who developed the disease. That means intervening during the prediabetes phases is important in reducing early complications, the researchers said.

The researchers were also unable to determine if diet and exercise or metformin were able to lower heart attacks and strokes as there weren’t enough events to test the treatments’ effect on cardiovascular disease, they said.

“Hopefully in the next five years or so we may be able to say something more definitively about the effect of our interventions on these complications,” Ronald Goldberg, a study investigator and a professor of medicine at the University of Miami, said in a telephone interview.

The study was funded by the U.S. National Institutes of Health.