What dietary advice did participants receive?
Participants were asked to lower fat to less than 25 percent of caloric intake. If reducing fat did not result in weight loss, a calorie goal was added. Participants received culturally sensitive training in diet, exercise, self-monitoring, goal-setting, and problem-solving. Participants took part in a 16-session core-curriculum during the first 24 weeks, then were seen individually or in groups at least every other month, and contacted by mail or phone on the alternate months. They were also invited to attend three group classes on healthy eating, physical activity, or behavioral topics that were offered each year, and to participate in periodic motivational campaigns with clinic competitions and group walking events.
Lifestyle intervention more effectively reduced diabetes risk than metformin. Within each arm, did certain groups of DPP participants benefit more from the intervention than other groups?
Lifestyle intervention worked in all of the groups, but it worked particularly well in people aged 60 and older, reducing the development of diabetes by 71 percent. This is an important and heartening discovery because as many as 20 percent of people aged 60 and older develop diabetes. Among those taking metformin, its effect in reducing diabetes risk was most pronounced in younger, heavier people--those 25 to 40 years old with a body mass index of 36 (about 50 to 80 pounds overweight).
Did the DPP volunteers in the lifestyle group benefit more from one lifestyle change than the other, e.g., more from exercise than from diet or vice versa?
The study wasn’t designed to examine the effect of exercise versus diet, so researchers can’t answer that question easily. However, they will perform secondary analyses that may provide some insight into this issue.
Lifestyle changes with diet and exercise reduced diabetes risk, as did treatment with metformin. By combining these interventions, could diabetes risk be reduced even further?
DPP researchers did not study the combination of lifestyle changes and metformin, so the joint effects of the two interventions are unknown.
Would the new formulation of metformin, Glucophage XR, be helpful to people with IGT?
The DPP researchers did not use Glucophage XR and therefore do not have any information about its potential value in preventing diabetes.
Do the DPP interventions affect the risk of cardiovascular disease, an important cause of mortality in people with type 2 diabetes?
DPP researchers are still analyzing the data and performing more studies to determine whether the interventions affected the development of atherosclerosis, which causes cardiovascular disease, or cardiovascular disease itself. These were important secondary outcomes in the study.
Are there any plans to get information about the DPP to the public and health care professionals?
The American Diabetes Association and NIDDK have a joint committee developing clinical recommendations for health care providers that will provide guidance on how the results of DPP can be applied to individual patients. The results of this work will be published in the next few months.
The National Diabetes Education Program (NDEP), a jointly sponsored initiative of the National Institutes of Health, the Centers for Disease Control and Prevention, and over 200 public and private organizations, has begun an effort to translate and disseminate messages and intervention strategies that derive from the DPP. The NDEP will be developing health messages and promoting diabetes treatment and prevention strategies for health professionals, people with diabetes and those at risk for the disease. This work is initially focused two areas: (1) developing and disseminating information and tools to help health care providers and people at risk for the disease to assess risk on an individual basis and (2) developing tools that health care providers and people at risk can use to attain and maintain the modest lifestyle changes that have been proven successful in preventing the onset of diabetes.
What is the estimated cost of the DPP interventions?
The DPP study group and PHS have been analyzing the cost effectiveness of the metformin and lifestyle interventions. Because the study ended early, these analyses are incomplete. The researchers hope to have an accurate estimate of the cost effectiveness or the cost benefit ratio for the interventions in the next six months.
Were there any deaths or serious injuries in the study resulting from metformin treatment or the lifestyle changes?
A total of 14 DPP participants died during the study. The rate of deaths was lower than the expected rate based on the overall U.S. population. Moreover, there were no significant differences between the number of deaths in the placebo, lifestyle, or metformin groups. None of the deaths was attributed to lifestyle changes or metformin.
Were there adverse effects associated with the interventions?
The only adverse effects linked to the interventions were diarrhea, which was reported more often by participants taking metformin, and musculoskeletal complaints associated with the lifestyle interventions.
What will happen to the volunteers who took part in the DPP?
The DPP researchers plan to continue following the DPP participants to learn more about the effects of these interventions on the development of diabetes.
What happened to the DPP volunteers who developed diabetes?
Those whose diabetes was well controlled with a fasting glucose of less than 140 mg/dl continued participating in the DPP and received advice on managing diabetes with their assigned intervention. If they needed other treatment, they were referred to their own physicians for further care.
Are diet and exercise beneficial even after diabetes develops?
Research has clearly shown that diet and exercise help people with type 2 diabetes control their blood glucose, blood pressure, and blood lipids in the short term. Although diet and exercise should lower the risk of developing cardiovascular disease and the other complications of diabetes, no long-term clinical trials have addressed this question. A recently launched trial, the Look AHEAD (Action for Health in Diabetes) study, will examine how diet and exercise affect heart attack, stroke, and cardiovascular-related death in people with type 2 diabetes.