Incidence rate trends in childhood Type 1 diabetes in Yorkshire, UK 1978-2007: effects of deprivation and age at diagnosis in the south Asian and non-south Asian populations

Aims Incidence of Type 1 diabetes in children is increasing worldwide. Earlier studies suggest that UK south Asian immigrants develop similar rates to the overall UK population, although incidence is lower in their country of origin. This study examines incidence rate trends of childhood Type 1 diabetes in Yorkshire 19782007, focusing on differences between south Asians and non-south Asians. Methods Data from the population-based Yorkshire Register of Diabetes in Children and Young People were used to estimate incidence (per 100 000 childhood population < 15 years per year) of Type 1 diabetes, stratified by sex, age and ethnicity validated using two name-recognition programs. Agesex standardized rates were calculated for 19782007 and assessed by ethnic-group and deprivation for 19902007. We used Poisson regression to assess incidence trends and predict rates until 2020. Results From 19782007, 3912 children were diagnosed. Overall incidence was 18.1 per 100 000 childhood population (< 15 years) per year (95% CI17.618.7) and increased significantly over time: 13.2 (19781987) to 17.3 (19881997) to 24.2 (19982007). Average annual percentage change was 2.8% (2.53.2). Incidence for non-south Asians (21.5; 20.722.4) was significantly higher than for south Asians (14.7; 12.417.1). Average annual percentage change increased significantly over 18 years (19902007) in non-south Asians (3.4%; 2.74.2) compared with a non-significant rise of 1.5% (-1.5 to 4.6) in south Asians. Deprivation score did not affect overall incidence. Conclusions Type 1 diabetes incidence rose almost uniformly for non-south Asians, but not for south Asians, contrary to previous studies. Overall rates are predicted to rise by 52% from 2007 to 2020 to 39.0 per 100 000 per year.