Drawing of a bar graph showing estimated total prevalence of diagnosed and undiagnosed diabetes in people ages 20 years and older, by age group, in the United States in 2007. The prevalence of diabetes in people ages 20 to 39 is about 2.6 percent. The prevalence of diabetes in people ages 40 to 59 is about 10.8 percent. The prevalence of diabetes in people ages 60 and older is about 23.8 percent. The source is the 2003 to 2006 National Health and Nutrition Examination Survey estimates of total prevalence including both diagnosed and undiagnosed diabetes, which were projected to 2007.