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Aims/hypothesis The aim of the study was to describe 20-year incidence trends for childhood type 1 diabetes in 23 EURODIAB centres and compare rates of increase in the first (1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998) and second (1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008) halves of the period. Methods All registers operate in geographically defined regions and are based on a clinical diagnosis. Completeness of registration is assessed by capture-recapture methodology.Twenty-three centres in 19 countries registered 49,969 new cases of type 1 diabetes in individuals diagnosed before their 15th birthday during the period studied. Results Ascertainment exceeded 90% in most registers. During the 20-year period, all but one register showed statistically significant changes in incidence, with rates universally increasing. When estimated separately for the first and second halves of the period, the median rates of increase -012-2571-8 were similar: 3.4% per annum and 3.3% per annum, respectively. However, rates of increase differed significantly between the first half and the second half for nine of the 21 registers with adequate coverage of both periods; five registers showed significantly higher rates of increase in the first half, and four significantly higher rates in the second half. Conclusions/interpretation The incidence rate of childhood type 1 diabetes continues to rise across Europe by an average of approximately 3-4% per annum, but the increase is not necessarily uniform, showing periods of less rapid and more rapid increase in incidence in some registers. This pattern of change suggests that important risk exposures differ over time in different European countries. Further time trend analysis and comparison of the patterns in defined regions is warranted.Diabetologia (2012) 55:2142-2147 DOI 10.1007/s00125

Before the onset of late complications, significant excess mortality existed following the diagnosis of type 1 diabetes in childhood, even in recent years. Variation between countries in this excess could not be explained.

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word count: 250 excluding headingsMain text word count: 2,564 including Table and Figure legends Tables and Figures: Tables (2) Methods Twenty-three population-based registers recorded date of diagnosis for new cases of type 1 diabetes among children under 15 years. Tests for seasonal variation in monthly counts aggregated over the 20 year period were conducted. Time series regression was used to investigate if sunshine hour and average temperature data were predictive of the 240 monthly diagnosis counts after taking account of seasonality and long term trends.Results Significant sinusoidal pattern was evident in all but two small centres with peaks in December to February and relative amplitudes ranging from 11% to 39% (median 18%). However, most centres showed significant departures from a sinusoidal pattern. Pooling results over centres, there was significant seasonal variation in each age-group at diagnosis, with least seasonal variation in those under 5 years. Boys showed greater seasonal variation than girls, particularly those aged 10-14 years. There were no differences in seasonal pattern between four five-year sub-periods. Departures from the sinusoidal trend in monthly diagnoses in the period were significantly associated with deviations from the norm in average temperature (0.8% reduction in diagnoses per 1 C excess) but not with sunshine hours.Conclusions/interpretation Seasonality was consistently apparent throughout the period in all age-groups and both sexes, but girls and the under 5s showed less marked variation. Neither sunshine hour nor average temperature data contributed in any substantial way to explaining departures from the sinusoidal pattern.

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.

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Our 21-yr study shows dynamic changes in incidence of childhood type 1 diabetes in Hungary, probably reflecting changes in the environment.