The large increase in incidence of Type I diabetes mellitus in Poland

Aims/hypothesis. A rising incidence of Type I (insulin-dependent) diabetes mellitus in different countries in Europe during the last decade has been r ecently reported. However, in the early 1990s, Poland was reported to have a stable low incidence of this disease. This study aimed to estimate the an nual incidence of Type I diabetes in a north-eastern region of Poland (Bial ystok region) and investigate if it is associated with age, sex, urban rura l differences and the season of disease onset. Methods. A register of patients with Type I diabetes using two independent sets of data sources was established in 1994 as part of the EURODIAB TIGER programme. The primary data sources were paediatric and internal medicine d ivisions of the hospitals in the Bialystok province and the secondary were outpatient diabetic clinics in the region. The degree of ascertainment was 98.5 % for the combinated data sources. Results. We found a significant rising trend in the incidence of Type I dia betes in children under 15 years of age (in 1998 the incidence was approxim ately twice as high as in 1994). Increasing incidence rates were observed i n the rural areas but not in urban populations. Seasonal variation in the i ncidence was also found, with a peak in winter and nadir in summer. Conclusions/interpretation. These results show that the north-eastern regio n of Poland is an area with a moderate rather than a low risk of Type I dia betes. Our observations confirm the important role of environmental and soc io-economic factors or both in the pathogenesis of Type I diabetes.