Drop to a healthy weight. It’s by far most important thing you can do for preventing diabetes.

Walk it off: In a study, people cut their risk of diabetes in half by exercising.

RODALE NEWS, EMMAUS, PA—According to the Centers for Disease Control and Prevention (CDC) in Atlanta, 54 million adult men and women in the U.S. have what docs call "pre-diabetes," which means their insulin levels are above normal but not high enough to be classified as type 2 diabetes. People with pre-diabetes are five to 15 times more likely than people with normal insulin levels to develop type 2 diabetes—unless, a new study of preventing diabetes indicates, they make a concerted effort to eat healthfully and exercise regularly. Then they’re protected—potentially for a very long time.

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.