Diabetes mellitus is associated with severe microvascular complications (e.g., kidney disease and eye disease) and macrovascular complications (e.g., stroke and ischemic heart disease). These complications can result in severe long-term complications (e.g., amputation, disability, and blindness) and account for a substantial economic burden. This report uses data from CDC's National Health Interview Survey (NHIS) to examine trends in the incidence and prevalence of self-reported diabetes in the United States during 1980-1994. The findings document increases in both the incidence and prevalence of diabetes during this period and suggest that most of the increase was attributable to factors other than the aging of the U.S. population.