Seasonal variation in month of diagnosis in children with type 1 diabetes registered in 23 European centers during 1989-2008: little short-term influence of sunshine hours or average temperature

Abstract

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.

Seasonality of diagnosis of type 1 diabetes mellitus in the Netherlands (Young Dudes-2)

“…This finding is in accordance with most previous studies on the seasonality of the diagnosis of T1DM [7,12,14,15,18,20]. Although an initial study from 2001 found no relationship between the incidence of T1DM diagnosis and the season among several countries in Europe, a recent study within Europe based on accumulated data from 23 European registries over a 20-year observation period reported seasonal variation in T1DM diagnosis with highest IR in November to February among all patients and in both sexes in most countries [20].…”

“…Recently, the Eurodiab study described seasonality with peak incidence in the winter in 21 of the 23 European countries included [20]. As the Netherlands has not been participating in this register since 1999, seasonality patterns in diagnosis of T1DM in the Netherlands are unknown.…”

Recent Incidence of Type 1 Diabetes Mellitus in Montenegro: A Shift Toward Younger Age at Disease Onset

“…The greatest number of cases were diagnosed during autumn and winter months. Seasonality in monthly case counts of T1DM is apparent in most EURODIAB centers, in all age groups and both sexes 6 . In conclusion, the results of this study indicated that T1DM incidence was still increasing in younger age groups, especially in boys aged 0-4 years.…”

“…Many registries describe seasonal variation in the date of T1DM diagnosis, with a note that the disease is most often diagnosed during winter months 6 . This is associated with the number of sunny days, which is important for the synthesis of vitamin D 7 and for seasonal infections 8 .…”

Evidence for the increase in the incidence of type 1 diabetes in children aged 0-14 years in the Republika Srpska, 2001-2016

“…Also, an additional explanatory factor for our results might be the fact that our country's climate is continental, meaning that we have sufficient sunny days, which also might contribute to the levels of vitamin D (13,14).…”