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 recently reported. However, in the early 1990s, Poland was reported to have a stable low incidence of this disease. This study aimed to estimate the annual incidence of Type I diabetes in a north-eastern region of Poland (Bialystok region) and investigate if it is associated with age, sex, urban rural 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 divisions 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 diabetes in children under 15 years of age (in 1998 the incidence was approximately twice as high as in 1994). Increasing incidence rates were observed in the rural areas but not in urban populations. Seasonal variation in the incidence was also found, with a peak in winter and nadir in summer. Conclusions/interpretation. These results show that the north-eastern region of Poland is an area with a moderate rather than a low risk of Type I diabetes. Our observations confirm the important role of environmental and socio-economic factors or both in the pathogenesis of Type I diabetes.