Twenty-one years of prospective incidence of childhood type 1 diabetes in Hungary--the rising trend continues (or peaks and highlands?).

The aim of this study was to examine secular trends in the incidence of type 1 diabetes in children aged 0-14 yr in Hungary over the period 1989-2009. Newly diagnosed children with type 1 diabetes aged 0-14 yr in Hungary were prospectively registered from 1989 to 2009. Primary ascertainment of cases was by prospective registration using hospital notifications. Case ascertainment was over 96% complete using the capture-recapture method. Standardized incidence rates were calculated and secular trends estimated using Poisson regression analysis. In Hungary during 1989-2009 a total number of 3432 children were identified, giving a standardized incidence rate of 12.5 [95% confidence interval (CI) 12.1-12.9] per 100,000 person yr. The overall incidence rate has doubled from 7.7 (95% CI 6.4-9.15) per 100,000 per yr in 1989 to 18.2 (95% CI 15.7-20.9) per 100,000 per yr in 2009. A significant linear trend in incidence (p < 0.001) has been observed over time, with a mean annual increase of 4.4%. The increase in incidence was present in both genders and in all age groups, with the largest relative increase in the youngest age group (6.2%; p < 0.001). The incidence of type 1 diabetes in Hungarian children continues to increase, with the highest rate in the very young. Although it seems that transient periods of stabilization followed by increases in incidence are apparent, the long-term trend continues to be steadily upward. Incidence of childhood type 1 diabetes is a dynamic process, probably reflecting the changes of the environmental exposures and continued registration is necessary to recognize these trends.