Background: The aim of this study was to investigate seasonality in the initial presentation of type 1 diabetes mellitus (T1DM) among Dutch children.
Methods: Observational, nationwide study in the Netherlands. Using the national registry for both healthcare reimbursement and pharmaceutical care, data of all Dutch children (aged 0-14 years) with a diagnosis of T1DM in the period 2009-2011 were obtained.
Results: During the study period (2009-2011) an average annual number of 2.909.537 children aged 0-14 lived in the Netherlands and 676 children were diagnosed with T1DM per year, translating into an annual incidence rate (IR) of T1DM of 23.2 per hundred thousand children (ptc). The annual IR differed significantly (p=0.03) between seasons: 6.4 ptc in winter, 4.9 ptc in spring, 5.4 ptc in summer and 6.6 ptc in autumn. This pattern was present within both boys and girls Conclusions: Among Dutch children aged 0-14 years, there is seasonality in the of T1DM with a peak incidence in autumn and winter.