Endocrine Abstracts (2008) 17 P54

Seasonality of disease onset and of birth in type 1 diabetes mellitus

M Bandhakavi & J Kirk


Birmingham Children’s Hospital, Birmingham, UK.


Background: It is recognised that the incidence of type 1 diabetes mellitus (T1DM) is increasing in the United Kingdom, especially in young patients (<5 y). Although seasonal variation in the onset of T1DM, with autumn and winter peaks, and also in the month of birth has been described, it was our perception that new patients were presenting throughout the year to our unit.

Methods: Data was available on 440 newly diagnosed cases of TIDM, (100, 173 and 167 cases of <5 years, 5–11 years and >11 years respectively), presenting to our unit over a 12 year period between 1996 and 2007. Data was analysed by month of presentation and by month of birth, both for the newly presenting group as a whole and also for different age groups.

Results: There was no increased incidence of T1DM as a whole or in the under 5s over the last 12 years. Monthly and seasonal comparison revealed that more children developed diabetes in January and February and in winter compared to other seasons, but this did not achieve statistical significance (P=0.09). Subgroup analysis based on age at diagnosis displayed a similar trend in the under 5s but not in the 5–11 or above 11 year olds. Seasonal variation was significant in the under 5s (P=0.03), but not in the other age groups. More winter born children, specifically the 5–11 and above 11 year olds developed diabetes compared to those in other seasons, but none of these was statistically significant.

Conclusions: Our data does not support the increased incidence of T1DM over the last decade or the rising number of younger (<5 y) patients. Our hospital, however, does not cover a clearly defined geographical area so this may not reflect the true incidence in population. A seasonal variation in incidence was found in the under 5’s but not older groups, whilst the converse was found for seasonal variation in month of birth, indicating possible different aetiologies.

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