Diabetes afflicts more than 16 million people in the United States; type 2 diabetes accounts for up to 95 percent of all diabetes cases. New findings from the Diabetes Prevention Program (DPP), a major clinical trial conducted by Massachusetts General Hospital (MGH) and 26 other medical centers nationwide, show that modifications in diet and exercise can dramatically delay the onset of type 2 diabetes in people predisposed to the disease. Participants randomly assigned to intensive lifestyle intervention reduced their risk of getting type 2 diabetes by 58 percent. The same study found that treatment with the oral diabetes drug metformin (Glucophage®) also reduces diabetes risk, though less dramatically. David Nathan, director of the MGH Diabetes Unit and national chair of the DPP study, is a professor of medicine at Harvard Medical School. The DPP is funded by the National Institute of Diabetes and Digestive and Kidney Diseases, the National Institute of Child Health and Human Development, the National Institute on Aging, the National Center on Minority Health and Health Disparities, the National Center for Research Resources, the Office of Research on Women’s Health, and the Office of Behavioral and Social Science Research within the NIH, plus other agencies.