Researchers from Finland have found a correlation between new cases of Type 1 diabetes and winter months.

The study analysed data of 31,000 children from 105 diabetes centres across 53 countries found a correlation between the season and the onset of Type 1 diabetes. Of the 42 centres that exhibited this seasonal trend, 28 centres had peaks of diagnosis in winter and 33 had troughs in summer.

Large study, strong correlation

Published in the journal 'Diabetic Medicine', the research also found that diabetes centres further away from the equator were more likely to have greater numbers of new cases in winter. This winter trend was more prevalent in boys, as well as in both sexes from the older age groups (5 to 14 years old).

"Results from previous studies in this area have been conflicting but this larger study shows a stronger correlation which is interesting, especially as we still don't know exactly why Type 1 diabetes develops", said Victoria King, Diabetes UK Research Manager.

"Investigating why we might be seeing this pattern could tell us more about what may be triggering the development of Type 1 diabetes.

"Despite this, the study looked at correlations over a relatively short period of time and not all centres that took part in the study showed the correlation between seasonality and diagnosis of Type 1 diabetes so more data are needed before more definite conclusions can be drawn", said King.

Viral infections

Lead author of the study, Elena Moltchanova, Statistician at the National Institute for Health and Welfare, Helsinki, said:

"Numerous reasons have been suggested for the apparent seasonality of the onset of Type 1 diabetes.

These include a seasonal variation in people's levels of blood glucose and insulin, seasonal viral infections, the fact that young people tend to eat more and do less physical activity during winter months and, similarly, that summer holidays provide a rest from school stress and more opportunity to play outdoors."

Diabetes UK