THE DETAILS: This study checked on the 3,000-plus participants in the Diabetes Prevention Program (DPP), a National Institutes of Health–sponsored study of people from 27 clinical centers across the United States who were overweight and had pre-diabetes. The original study’s aim was to find out whether modest weight loss (the goal was a weight loss of 7 percent) through dietary changes and greater physical activity would be effective at delaying or preventing diabetes—and whether treatment with an oral diabetes drug, metformin, could do the same thing. What the researchers found after nearly three years was that, compared with people who made no changes, study participants taking metformin reduced their risk of developing diabetes by 31 percent. Those who simply ate healthier and exercised more (putting in at least 150 minutes of physical activity per week) reduced their risk by a whopping 58 percent.
The current study followed up on those results, checking in on DPP participants 10 years later. What the researchers found was that diabetes diagnoses in the decade after the end of the original study remained lowest for the group who ate healthier and exercised more.
WHAT IT MEANS: Diet and exercise can significantly delay the onset of diabetes—even better than drugs can—by improving the ability of your muscle cells to use insulin. That much we’ve long known. What this study demonstrates is that the combined effect of exercise and healthful eating endures. “What sets our study apart is the long duration of follow-up,” says epidemiologist Richard F. Hamman, MD, DrPH, dean of the Colorado School of Public Health, vice-chair of the national Diabetes Prevention Program Outcomes Study, and principal investigator of the Colorado clinical site for the study. “We’ve shown that diabetes can be prevented or delayed over 10 years. That’s a very long period.”
Here’s how to cut your risk of diabetes and keep it low—for a very long time:
• Exercise and eat healthy. That’s what the DPP participants did, with great success. The DPP wasn’t designed to reveal which—diet or exercise—benefited the participants more, although the researchers are now performing secondary analyses that may provide some sort of clue. For the time being, however, you gotta do both.
• Drop to a healthy weight. It’s the single most important thing you can do to avoid diabetes. In fact, says Dr. Hamman, it’s so significant, it would occupy all three spots on his list of the top three things you need to do to reduce your risk of diabetes. “Weight loss, weight loss, weight loss,” he says. And every little bit counts. The DPP study participants strove to lose 7 percent of their body weight by reducing fat content to less than 25 percent of total calories they ate, and by exercising at least 150 minutes per week. "We showed in a prior paper that if you didn’t lose 7 percent of your weight, but were able to lose 1 percent (or two to three pounds), you could still reduce your risk of diabetes by 16 percent," Dr. Hamman says. "So small changes can make a big difference.”
• Work out 30 minutes a day, five times a week. That’s what the study participants did—usually, says Dr. Hamman, by walking. And it worked.
• Talk with your doctor about medication. While the risk reduction enjoyed by the DPP participants who took metformin wasn’t as great, on average, as that earned by the diet-and-exercisers, it, too, reduced diabetes risk long-term—especially, points out Dr. Hamman, in overweight persons who were unable to change their lifestyles. A healthy diet and good exercise habits are important for everyone, but check in with your doctor if you need other options.