Secular trends in the prevalence of diabetes and impaired glucose tolerance in urban South India - the Chennai Urban Rural Epidemiology Study (CURES-17)

Aims/hypothesis: The aim of this study was to determine the secular trends in prevalence of diabetes and IGT in urban India. Materials and methods: The Chennai Urban Rural Epidemiology Study (CURES) screened 26,001 individuals aged >= 20 years using the American Diabetes Association fasting capillary glucose criteria. The study population, which was representative of Chennai, was recruited by systematic random sampling. Every tenth subject from Phase 1 of CURES was invited to participate in Phase 3 for screening by World Health Organization (WHO) plasma glucose criteria. The response rate was 90.4% (2,350 responders from 2,600 potential subjects). The prevalences of diabetes and IGT in CURES were compared with three earlier studies: two conducted on a representative population of Chennai in 1989 and 1995, and the other the National Urban Diabetes Survey (NUDS) completed in 2000. Results: The overall crude prevalence of diabetes using WHO criteria in CURES was 15.5% (age-standardised 14.3%), while that of IGT was 10.6% (age-standardised 10.2%). Prevalence of diabetes increased by 39.8% (8.3-11.6%) from 1989 to 1995; by 16.3% (11.6-13.5%) between 1995 and 2000; and by 6.0% (13.5-14.3%) between 2000 and 2004. Thus within a span of 14 years, the prevalence of diabetes increased by 72.3% (chi(2) trend 22.23, p < 0.0001). The prevalence of IGT increased by 9.6% from 1989 to 1995 and by 84.6% between 1995 and 2000 (chi(2) trend 52.9, p < 0.0001). However, it decreased by 39.3% between 2000 and 2004 (p < 0.0001). There was a shift in the age at diagnosis of diabetes to a younger age in CURES compared with NUDS. Conclusions/interpretation: Compared with earlier studies, the prevalence of diabetes in Chennai, representing urban India, has increased while that of IGT has decreased.