A community-based survey on diabetes mellitus (DM) and impaired glucose tolerance (IGT) was carried out in 11 provinces/autonomous regions/municipalities of China from July 1995 to June 1997, using stratified cluster sampling method and diagnostic criteria recommended by WHO. A total number of 42,751 persons aged 20-74 years having lived in the communities longer than 5 years, were selected as research subjects. Results showed that the prevalence rates of DM and IGT standardized by age were 3.21% (95% CI: 3.05%-3.37%) and 4.76% (95% CI: 4.56%-4.96%) respectively; with a ratio of DM to IGT 1:1.5. The prevalence rates of DM and IGT increased parallelly with the increase of age. Among the 20-39 years old, the prevalence rates of DM and IGT were 1.01% and 2.70% respectively, while both of them exceeded 7% and 11% among people aged 50-59 years and above 60 years.