Steep increase of incidence of childhood diabetes since 1999 in Austria. Time trend analysis 1979-2005. A nationwide study.

In a prospective population-based incidence study all newly diagnosed type 1 diabetic patients 0-<15 years of age were registered by the Austrian Diabetes Incidence Study Group. The nationwide incidence of type 1 diabetes between 2000-2005 was compared with the previously published incidence rates. Long-term trends as well as seasonal trends were estimated by Poisson regression models. A total of 3,599 incident cases (1,908 boys; 1,691 girls) were identified. Case ascertainment was >92%. The overall incidence rate doubled from 7.3 (95% CI; 6.8-7.9)/100,000 in the period 1979-84 to 14.6 (95% CI, 13.7-15.4)/100,000 in the time period 2000-2005. A significant increase during the observation period of 26 years could be demonstrated in all age groups and both sexes (p<0.01), with the steepest increment during the last 5 years. Until 1994 the incidence rate in children 0-<5 years was rather stable, but afterwards increased dramatically with 9.2% (95% CI, 5.2-13.4) annually. Despite this steep increase in time trend, we did not observe a seasonal variation in this age group (0-<5) in contrast to significant seasonal variations in the groups 5-<10 and 10-<15 years of age. Over the past 26 years incidence of type 1 diabetes in childhood increased clearly in Austria. The steepest rise was observed in the last 5 years and in the younger age groups.