Lifestyle Changes Help Prevent Diabetes

Diet and exercise can dramatically reduce the risk of developing type 2 diabetes among the one out of 26 Americans at highest risk for the disease, according to a large clinical trial conducted by the National Institutes of Health (NIH). The results of the Diabetes Prevention Program (DPP) showed a 58 percent decreased risk of developing type 2 diabetes among study participants who followed a reduced-calorie, low-fat diet combined with 150 minutes of moderate physical activity per week. Eating well and getting active were found to be more effective than taking diabetes medication, which also reduced onset of diabetes to a lesser extent.

Researchers ended the study 1 year early in light of its impressive results, which were unveiled at a meeting of NIDDK’s Diabetes Mellitus Interagency Coordinating Committee and DHHS news conference on August 8, 2001. The 3-year study followed 3,234 adults with impaired glucose tolerance—the inability to process glucose efficiently resulting in elevated blood sugar levels, a condition that often precedes type 2 diabetes. All study participants were overweight or obese, with an average body mass index (BMI) of 34. Forty-five percent were from minority groups that have particularly high levels of type 2 diabetes—African Americans, Hispanic Americans, Asian Americans and Pacific Islanders, and American Indians. Participants ranged in age from 25 to 85 years, with an average age of 51.

"Lifestyle intervention worked as well in men and women and in all the ethnic groups."

Study participants were randomized to one of three groups: the intensive lifestyle intervention group; the drug treatment group, which received the glucose-lowering drug metformin; and the placebo
or control group. Members of the lifestyle group received culturally sensitive training in diet, exercise, self-monitoring, goal-setting, and problem-solving through a 16-session, 24-week curriculum. For the rest of the study, each participant met with a case manager monthly and attended periodic refresher classes and motivational events. The drug treatment and placebo groups also received educational materials and a half-hour counseling session on diet and exercise.

The lifestyle intervention group met the study goal of a loss of 7 percent of body weight—or roughly 15 pounds—in the first year, and maintained an average 5 percent loss over the course of the study. Fourteen percent of lifestyle participants developed diabetes by the end of the study, as compared to 22 percent in the metformin group and 29 percent in the placebo group.

“Lifestyle intervention worked as well in men and women and in all the ethnic groups,” said David Nathan, M.D., study chairman and director of the General Clinical Research Center at Massachusetts General Hospital in Boston. “It also worked well in people age 60 and older, who have a nearly 20 percent prevalence of diabetes, reducing their development of diabetes by 71 percent.” Metformin was not effective in this age group, nor in those who were less overweight.

A recently published study from Finland found the same 58 percent risk reduction among individuals who made intensive diet and physical activity changes. Whereas the Finnish study followed a fairly homogenous European populace, the DPP demonstrated the effectiveness of lifestyle intervention throughout America’s diverse population, among whom the prevalence of type 2 diabetes has tripled over the last 30 years.

The long-term effectiveness of lifestyle changes in delaying the onset of diabetes is uncertain. Nevertheless, “every year a person can live free of diabetes means an added year of life free of the pain, disability, and medical costs incurred by this disease,” said Allen Spiegel, M.D., director of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), which sponsored the DPP. “The DPP findings represent a major step toward the goal of containing and ultimately reversing the epidemic of type 2 diabetes in this country.” The results of the study were published in the February 7, 2002 New England Journal of Medicine. s