A Decade Later, Both Lifestyle Changes and Metformin Still Lower Type 2 Diabetes Risk
Study Reports on Persistence of Benefits Seen in the Diabetes Prevention Program
In 2002, the landmark randomized clinical trial, the Diabetes Prevention Program (DPP), reported outcomes 1 year early because of significant, positive study results. This study involved 3,234 adults at high risk for developing type 2 diabetes who were randomized to three treatment groups. The intensive lifestyle change group aimed at modest weight loss reduced the rate of developing type 2 diabetes over 3 years by 58 percent compared with the control group. Subsequently, DPP researchers provided support for lifestyle change to all participants in the DPP and followed participants to determine whether the benefit of intensive lifestyle intervention persisted over time. Now, after following the participants for a total of 10 years after enrollment in the DPP, the Diabetes Prevention Program Outcomes Study (DPPOS) found that the early intensive lifestyle intervention reduced the rate of developing type 2 diabetes by 34 percent over 10 years. The results appeared online October 29, 2009, in The Lancet.
In addition to the intensive lifestyle change group, DPP participants were also randomly assigned to receive treatment with the oral diabetes drug metformin. This group had a 31 percent reduced rate of diabetes in the DPP. Continued medication was offered to this group in the DPPOS, and the researchers found an 18 percent reduced rate of developing diabetes after 10 years, compared with placebo.
Participants in the DPP who were randomly assigned to make lifestyle changes also had more favorable cardiovascular risk factors, including lower blood pressure and triglyceride levels, despite taking fewer drugs to control their heart disease risk.
"In 10 years, participants in the lifestyle change group delayed type 2 diabetes by about 4 years compared with placebo, and those in the metformin group delayed it by 2 years. The benefits of intensive lifestyle change were especially pronounced in the elderly. People age 60 and older lowered their rate of developing type 2 diabetes in the next 10 years by about half," said David M. Nathan, M.D., director of the Diabetes Center at Massachusetts General Hospital and DPP/DPPOS chair.
In the United States, about 11 percent of adults-24 million people-have diabetes, and up to 95 percent of these adults have type 2. An additional 57 million adults, based on a 2007 estimate, have glucose levels that are higher than normal but not yet in the diabetic range, a condition called prediabetes, which substantially raises the risk of a heart attack or stroke and of developing type 2 diabetes in the next 10 years.
"The spiraling epidemics of obesity and type 2 diabetes in the United States and worldwide show no signs of abating," said Griffin P. Rodgers, M.D., M.A.C.P., director of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). "Millions of people could delay diabetes for years and possibly prevent the disease altogether if they lost a modest amount of weight through diet and increased physical activity."
Striking as the DPP findings were, the researchers did not know how long the benefit would endure, because DPP results were based on just 3 years of data. During a bridge period from January to July 2002, all participants were told the study's results and were offered the 16-session intensive lifestyle change program. The metformin group was also offered continued metformin therapy in the DPPOS. The majority of the DPP volunteers-88 percent-chose to participate in the DPPOS.
Intensive Lifestyle Changes
In the DPP trial, the intensive lifestyle change included lowering fat and calorie intake and increasing regular physical activity up to 150 minutes per week. Participants in this lifestyle intervention group received training in diet, exercise,In the DPP's first year, this group lost 15 pounds on average, but those followed in the DPPOS regained all but about 5 pounds from their starting weight over 10 years. The metformin group lost about 5 pounds during the DPP study, and this loss in weight was maintained in those followed in the DPPOS. The placebo control group lost less than 2 pounds over the decade.
About 5 to 6 percent of those in the lifestyle intervention group developed type 2 diabetes annually, an incidence rate that remained steady throughout the DPPOS. When the DPP ended in 2001, the metformin and placebo groups developed diabetes at the rate of 8 and 11 percent a year, respectively. However, 10 years after randomization of the DPP participants, the yearly diabetes incidence rates for those in the DPPOS metformin and original DPP control groups also fell to about 5 to 6 percent.
Researchers are looking at a number of explanations for the convergence of diabetes incidence rates for the three DPP groups. One possibility is that lifestyle change adopted by the metformin and placebo groups after the DPP ended lowered their rate of type 2 diabetes over time.
The DPP and the DPPOS have been funded by the NIDDK and other National Institutes of Health Institutes and Centers, with additional funding from the Indian Health Service, the Centers for Disease Control and Prevention, the American Diabetes Association, and the private sector.
The NIDDK offers free easy-to-read booklets and fact sheets about diabetes, including a fact sheet about the DPP. For more information or to obtain copies, visit www.diabetes.niddk.nih.gov.
NIH Publication No. 10-4562
Page last updated: December 5, 2011