Incidence of childhood-onset Type 1 diabetes mellitus in Devon and Cornwall, England, 1975-1996

To determine the incidence of Type 1 diabetes mellitus (DM) in children aged 0-15 years in the far south-west of England between 1975 and 1996.

Patient information was collected to set up the Cornwall and Plymouth Children's Diabetes Register (CPCDR) through two main data sources; hospitals and the general practitioners in all surgeries in the study region. All children under 16 years living within Cornwall and the Isles of Scilly, and the former Plymouth Health Authorities and diagnosed as having Type 1 DM during the study period were included. The case ascertainment was estimated by a capture-recapture method. Trends and differences in incidence of sex, age, time period and district of diagnosis were analysed by Poisson regression analysis. Roger's method was used to estimate the seasonal variations.

A total of 522 subjects aged between 0 and 15 years were identified from 01/01/1975 to 31/12/1996, giving an overall crude incidence of 14.9/ 100 000 population/year. The case ascertainment was 94.4% (95% confidence interval (CI) 91.4- 97.6%) for the whole register. Poisson regression analysis showed that a significant increase of incidence (2.49% per year) was observed throughout the 22-year study period, which was mainly a result of the significant increase in the 0-4 year age-group (6.29% per year). The incidence significantly differed among the 22-years (P = 0.007), the three age groups (0-4, 5-9 and 10-14 years, P<0.001) and different sexes (P=0.049). The significant seasonal variations were detected with peak incidence appearing in autumn and winter.

The first validated childhood-onset diabetes register has been set up in the far south-west of England. The incidence of childhood Type 1 DM in this region has increased significantly over the past two decades, especially in children under 5 years.