In 2010, an estimated 18.8 million persons in the United States had diagnosed diabetes mellitus and another 7.0 million had undiagnosed diabetes. Since 1990, the prevalence of diagnosed diabetes in the United States has risen sharply among all age groups, both sexes, and all racial/ethnic groups for which data are available. To learn whether the increase has been greater in some regions of the United States than in others, data on self-reported diabetes in adults collected during 1995-2010 by the Behavioral Risk Factor Surveillance System (BRFSS) were analyzed. The analysis showed that the age-adjusted prevalence of diagnosed diabetes increased during the interval in every state, the District of Columbia (DC), and Puerto Rico. In 1995, age-adjusted prevalence was ≥6% in only three states, DC, and Puerto Rico, but by 2010 it was ≥6% in every state, DC, and Puerto Rico, and ≥10.0% in six states and Puerto Rico. Strategies to prevent diabetes and its preventable risk factors are needed, especially for those at highest risk for diabetes, to slow the rise in diabetes prevalence across the United States. Continued surveillance of diabetes prevalence and incidence, its risk factors, and prevention efforts is important to measure progress of prevention efforts.