Trends in the incidence of childhood diabetes in south Asians and other children in Bradford, UK

Aims To investigate incidence rates and time trends, over 21 years, of Type 1 diabetes in a migrant population of south Asian children in Bradford, UK. Methods Children (0-14 years) living in the city of Bradford and diagnosed with Type 1 diabetes were selected from a population-based region-wide register. Between 1978 and 1998, 289 new-onset cases were registered and classified as south Asian (Indian, Pakistani, Bangladeshi) or not, based on their full name using two different computer algorithms and visual inspection. Results Sixty-six children (22.8%) were designated as south Asian with 223 (77.2%) remaining. The overall age-sex standardized incidence for south Asian and non-south Asian children was 13.0 per 100 000 person years (95% confidence interval 9.9-16.2) and 12.9 (11.2-14.6), respectively. Rates were similar for south Asians at all ages, whereas for the mainly Caucasian children incidence differed significantly by age group (P < 0.001). An average annual increase in incidence of 4.3% (P = 0.001) was seen for all children compared with 6.5% in south Asians (P = 0.002) and 2.4% (P = 0.128) in non-south Asians. Conclusions Children in south Asia have a low incidence of Type 1 diabetes but migrants to the UK have similar overall rates to the indigenous population. However, a more steeply rising incidence is seen in the south Asian population, and our data suggest that incidence in this group may eventually outstrip that of the non-south Asians. Genetic factors are unlikely to explain such a rapid change, implying an influence of environmental factors in disease aetiology. The similarity in rates by age group in the south Asian population is notable.