A survey conducted in 1988-1989, in the city of Madras, South India, showed that the prevalence of diabetes mellitus in adults was 8.2% and prevalence of impaired glucose tolerance (IGT) was 8.7%. The present survey was another cross-sectional study conducted 5 years later in the same urban area to study the temporal changes in the prevalence of diabetes and IGT. The two sample populations surveyed were similar in age structure and socioeconomic factors. In the second survey in 1994-1995, a total of 2,183 subjects, 1,081 men and 1,102 women, with a mean age of 40 +/- 12 years were tested by an oral glucose tolerance test; fasting and 2-h post-glucose plasma glucose were measured. Anthropometric measurements, details of physical activity and clinical history of diabetes were recorded. Age-standardised prevalence of diabetes had increased to 11.6% from 8.2% in 1989 and IGT was 9.1%, similar to 8.7% in 1989. Multiple regression analysis showed age, waist:hip ratio, body mass index (BMI) and female sex were correlated to diabetes. Family history of diabetes showed interaction with age and BMI. Prevalence of IGT correlated to age, BMI and waist:hip ratio. This study highlights the rising trend in the prevalence of non-insulin-dependent diabetes (NIDDM) in urban Indians. The persistent high prevalence of IGT may also be a predictor of a further increase in NIDDM in the future. No significant differences in the anthropometric data were noted in this compared to the previous study.