Epidemiology of Type I diabetes mellitus in Switzerland: steep rise in incidence in under 5 year old children in the past decade

Aims/hypothesis. In this nationwide prospective study we wanted to verify t he trend of increasing diabetes incidence data from our earlier retrospecti ve analysis of the military registry of Swiss men. Subjects and methods. The data collection of newly diagnosed children in Sw itzerland at an age younger than 15 years started in 1991. The countrywide survey used a small questionnaire which was sent back to the study centre. The questionnaire was anonymous and contained: hospital of diagnosis, initi als, sex, birth date, date of diagnosis, residence, country of citizenship, and responsible physician. General data on the population were taken from publications of the Swiss Federal Statistical Office. Results. A total of 941 children below the age of 15 years with newly diagn osed Type I (insulin-dependent) diabetes mellitus were collected (434 girls , 507 boys). The incidence in children aged 0 to 14 years rose significantl y between 1991 and 1999 with a yearly average increase of 5.1%. In the age group 0 to 4 years a more than four-fold increase in incidence from 2.4/100 000 per year to 10.5/100 000 per year (p = 0.0002) was recorded, whereas t he age-specific incidence in the 5 to 9-year-old and 10 to 14-year-old chil dren did not change during the data collection period. The incidence was si gnificantly higher in boys than in girls, whereas no difference was found b etween rural and urban populations. Conclusion/interpretation. The incidence of Type I diabetes is rising in ch ildren living in Switzerland but only the youngest age group of under 5 yea rs of age is affected showing a large annual average increase of 23.8%.