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 count ries. Minor area variations have been reported in some northern and souther n European countries. We analyzed the regional pattern of childhood diabete s in entire Austria over a 10-year study period. Methods: Newly diagnosed patients < 15 years of age were prospectively regi stered on a nation-wide basis from 1989 to 1999. Cases were allocated to po litical districts and provinces using the postal code of residence. Bayesia n smoothing techniques were used for calculating incidence rates. Time tren ds 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 abou t 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 - t he 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 registe red 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 melli tus in both sexes and all age groups and the spatial clustering in the east ern part of the country underlines the importance of environmental factors.