How to Avoid Diabetes -- Landmark Results Unveiled
Diet and Exercise Really Work to Prevent Diabetes
By Sean Martin
WebMD Washington Correspondent
Reviewed by Gary D. Vogin MD
Aug. 8, 2001 (Washington) -- Either a low-fat diet combined with moderate exercise or the drug metformin -- brand name Glucophage -- dramatically reduced type 2 diabetes risk among overweight people with elevated blood sugar, according to landmark study results released today by the National Institutes of Health (NIH).
The findings are crucial for battling the nation's "surging epidemic" of type 2 diabetes, said Allen Spiegel, MD, director of the National Institute of Diabetes and Digestive and Kidney Diseases at the NIH.
"For the first time, we know that type 2 diabetes can be prevented," said Christopher Saudek, MD, president of the American Diabetes Association. "It may be as simple a solution as getting up off the couch and eating a healthier diet."
"This really puts prevention on the map," said David Nathan, MD, a Harvard Medical School professor who led the $174-million government-sponsored study.
Indeed, the study found that the diet/exercise program cut diabetes risk by 58%. Metformin was significantly less effective, but still decreased risk by 31%. Both approaches worked equally well among diverse ethnic and racial groups.
The diet/exercise changes worked especially well among people age 60 and older, whereas metformin worked best in younger and heavier individuals.
Type 2 diabetes, which represents the vast majority of diabetes cases, has tripled in prevalence over the last 30 years, largely due to a huge explosion in obesity. Since 1960, the percentage of Americans who are obese has roughly tripled.
More than 16 million Americans have diabetes; 8% of all Americans older than 20 have type 2 diabetes. The chronic disease is the nation's leading cause of kidney failure, blindness, and limb amputations. Blacks and Hispanics suffer an especially high rate of the disease.
According to Spiegel, some 10 million Americans would fit the health profile of the people in this diabetes study. The study's 3,234 participants were overweight, with an average body mass index of 34. They also had pronounced "impaired glucose tolerance," meaning a 2-hour postprandial blood glucose level between 140 and 199 mg/dL.
The average age of patients in the study was 51, although ages ranged from 25 to 85. Close to 1,000 of the patients were randomly put on a low-fat diet and told to engage in moderate physical exercise, such as walking for 30 minutes.
The diet was centered around lowering fat intake to less than 25% of overall calories, but those in the study also got training in goal-setting and problem-solving and were invited to participate in group events.
Spiegel said that the 30-minute daily exercise regime "should be easily achievable" by most nondiabetic overweight Americans with high blood sugar levels.
Not only did making these lifestyle changes reduce their risk of getting diabetes by 58%, but these individuals also lost 5%-7% of their body weight. Scientists believe weight loss can lower diabetes risk by reducing insulin resistance.
Another 1,000 or so patients took metformin, and a third group of 1,000 took placebo pills.
Metformin is already a highly profitable drug for Bristol Myers Squibb; it was approved by the FDA in 1995 for treating type 2 diabetes. The drug does not yet, however, have clearance for use in preventing diabetes. The drug is off-limits for people with kidney or liver problems or for heavy drinkers.
Tommy Thompson, President George W. Bush's secretary for Health and Human Services, said the study's results proved that "prevention works." He said his agency would work on recommendations, to be issued by the end of the year, to help put the results into national practice.
Meanwhile, researchers still have numerous unanswered questions. Can diet/exercise or metformin prevent diabetes indefinitely? Those in the study have only been followed for 3 years. "We simply don't know how long, beyond the 3-year period studied, diabetes can be delayed," said Nathan.
And could metformin and the diet/exercise changes together provide an even greater benefit than either does alone?
"One could speculate that [metformin] would be additive, but it may be that once you get to 58% reduction with the lifestyle [changes], you can't do any better than that," Nathan tells WebMD. "It's just unknown. We'd all like to know whether it would make a difference."