The Diabetes Prevention Program (DPP) and its follow-up study, the DPP Outcomes Study (DPPOS), have significantly impacted the approach to type 2 diabetes prevention worldwide. Sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), these studies have demonstrated the effectiveness of lifestyle changes and metformin in delaying or preventing the onset of type 2 diabetes in individuals at high risk.
DPP: Preventing Diabetes Through Lifestyle and Metformin
Initiated in 1996, the DPP was a randomized, controlled clinical trial conducted across 27 clinical centers in the United States. The study enrolled 3,234 participants at high risk for type 2 diabetes, including those with a family history of the disease, women with a history of gestational diabetes, and individuals from racial and ethnic minority groups. Participants were randomly assigned to one of three groups: a lifestyle change group, a metformin group, or a placebo group.
The lifestyle change group received intensive training aimed at achieving a 7% weight loss through dietary changes and increased physical activity (150 minutes per week). Participants in the metformin group received 850 mg of metformin twice daily, while the placebo group received a placebo. All participants received standard advice about diet and physical activity.
After approximately 3 years, the DPP revealed that participants in the lifestyle change group reduced their risk of developing type 2 diabetes by 58% compared to the placebo group. The lifestyle intervention was effective across all participating racial and ethnic groups, as well as in both men and women. Notably, participants aged 60 and older experienced a 71% reduction in their chances of developing type 2 diabetes.
Participants in the metformin group experienced a 31% reduction in their risk of developing type 2 diabetes compared to the placebo group. Metformin was particularly effective in women with a history of gestational diabetes, individuals aged 25 to 44, and those with a body mass index (BMI) of 35 or higher.
DPPOS: Long-Term Outcomes and Continued Monitoring
The DPP Outcomes Study (DPPOS) began in 2002, following the original DPP participants to assess the long-term effects of the interventions. The DPPOS aimed to determine whether the lifestyle change program or continued metformin use could delay the development of type 2 diabetes and reduce the incidence of other health problems, such as cardiovascular diseases, cancer, nerve damage, kidney disease, eye disease, and age-related cognitive and physical decline.
At the 10-year follow-up, participants in the lifestyle change group continued to experience a 34% delay in the development of diabetes compared to the placebo group, developing diabetes approximately 4 years later. Participants aged 60 and older in the lifestyle change group had a 49% delay in diabetes development. Those who continued to take metformin had an 18% delay in diabetes development, about 2 years later than the placebo group.
Fifteen-year follow-up data showed that participants in the lifestyle change group maintained a 27% reduction in diabetes risk compared to the placebo group, while those on metformin had an 18% reduction. Approximately 55% of participants in the lifestyle change group and 56% of those on metformin developed diabetes, compared to 62% in the placebo group.
Current Focus and Scalable Interventions
Currently, the DPPOS is in its third phase, initiated in early 2016, and is funded by the NIDDK in partnership with the National Heart Lung and Blood Institute (NHLBI) and National Cancer Institute (NCI). This phase aims to determine if metformin reduces the rates of cardiovascular diseases and cancer in high-risk individuals.
Building on the success of the DPP, the NIDDK has supported the development of modified, cost-effective versions of the DPP Lifestyle Change Program. One such version, tested in YMCAs, is now widely available in the United States through a partnership with the CDC’s National Diabetes Prevention Program. Since 2018, Medicare covers participation in the CDC’s National Diabetes Prevention Program for eligible individuals, increasing access to these vital interventions.
