Changes in age at diagnosis of type 2 diabetes mellitus in the United States, 1988 to 2000

PURPOSE The prevalence of diabetes in the United States is increasing. There is also concern that diabetes may be occurring at a greater frequency in youth and in young adults. We describe US population trends in self-reported age at diagnosis of type 2 diabetes mellitus. METHODS We undertook a secondary analysis of data from the National Health and Nutrition Examination Survey (NHANES) 1999-2000 and NHANES III (19881994). Both surveys are stratified, multistage probability samples targeting the civilian, noninstitutionalized US population, which allow calculation of population estimates. We included adults aged 20 years and older. We compared self-reported age at diagnosis of type 2 diabetes between the 2 survey periods. RESULTS The mean age at diagnosis decreased from 52.0 to 46.0 years (P < .05). Racial and ethnic differences in age at diagnosis found in 1988 to 1994 are no longer found in 1999 to 2000. CONCLUSIONS The age at diagnosis of type 2 diabetes mellitus has decreased with time. This finding likely represents a combination of changing diagnostic criteria, improved physician recognition of diabetes, and increased public awareness. Younger age at diagnosis may also reflect a true population trend of earlier onset of type 2 diabetes.