Increase in the incidence of type 1 diabetes mellitus in children in three cities in Poland, 1987-1999.

The aim of this study was to evaluate the trends in the incidence of type 1 diabetes mellitus (DM) in children aged 0-14 years between 1987 and 1999 in three cities in Poland. The study area comprised the provinces of Cracow and Wroclaw and the city of Warsaw. The data were collected prospectively on the basis of the register within the framework of the EURODIAB study up till 1997 and then within the project of the Ministry of Health. During the 13 years of the study period, 766 children (380 girls, 386 boys) with newly diagnosed type 1 DM were identified. The overall age-standardized incidence rates were 8.4/100,000 standardized population/year (95% CI 7.4-9.3) for Cracow province, 6.5/100,000/year (95% CI 5.6-7.4) for Wroclaw province and 7.9/100,000/year (95% CI 6.9-8.8) for Warsaw. A significant trend of increase for children aged 0-14 years was found in the three cities. The analysis of the trend in age subgroups showed a significant increase in incidence in all three age subgroups in Warsaw and Cracow province (0-4 year-old children, p <0.05; 5-9 year-olds, p <0.001 in Cracow province, p <0.05 in Warsaw, and in 10-14 year-olds, p <0.05 in Cracow province, p <0.005 in Warsaw). In the Wroclaw province a significant increase was observed in children aged 0-4 years (p <0.05) and 5-9 years (p <0.001). In children aged 10-14 years the increase was not statistically significant. The results of our study showed that the incidence of type 1 DM in children is rising. A similar phenomenon is occurring in many other countries. The greatest increase of incidence was observed in the 5-9 year-old subgroup of children in Cracow and Wroclaw provinces and in children aged 10-14 years in Warsaw. The incidence rates in excess of 9.0/100,000 per year observed since 1996 have placed Poland in the group of countries with low to medium incidence.