Regional distribution of childhood onset diabetes mellitus in Austria -: Analysis of national registration from 1989 to 1999

The incidence of type 1 diabetes mellitus in childhood varies between countries. Minor area variations have been reported in some northern and southern European countries. We analyzed the regional pattern of childhood diabetes in entire Austria over a 10-year study period. Methods: Newly diagnosed patients < 15 years of age were prospectively registered on a nation-wide basis from 1989 to 1999. Cases were allocated to political districts and provinces using the postal code of residence. Bayesian smoothing techniques were used for calculating incidence rates. Time trends were estimated with Poisson regression models. Results: The mean incidence per 100,000 was 9.2 (95% Cl 8.5-9.9) for girls and 10.2 (95% CI 9.5-10.9) for boys. A linear increase in incidence of about 2.1% per year, independent of age and sex, was noted for type I diabetes mellitus in Austria. A significant west to east gradient was also found - the risk was significantly increased in eastern provinces (RR 0.66-0.92 vs. RR 1.07-2.16, p < 0.01). The lowest incidence (7.3) per 100,000 was registered in Vorarlberg (95% CI 5.5-9.6) and the highest (12.1) in Burgenland (95% Cl 9.3-15.5). Conclusion/interpretation: The registered increase in type 1 diabetes mellitus in both sexes and all age groups and the spatial clustering in the eastern part of the country underlines the importance of environmental factors.