Children under 15 are more likely to develop diabetes in winter, a large international study suggests.

Analysis of data of 31,000 children from 105 diabetes centres in 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.

This winter trend was more prevalent in boys as well as in both sexes from the older age groups (5 to 14 years old).

The study, published in the journal Diabetic Medicine, also found that diabetes centres further away from the equator were more likely to have greater numbers of new cases in winter.

A total of 23,000 children in Britain have been diagnosed with Type 1 diabetes, the fourth-highest incidence in Europe, but the exact causes of the condition are unclear.

In contrast to Type 2 diabetes, which is associated with obesity and more likely to develop in middle age, the Type 1 form typically arises in childhood and requires lifelong supplements of insulin.

The condition develops when the insulin-producing cells in the pancreas have been destroyed. It is not known for sure why these cells have been damaged but the most likely cause is an abnormal reaction of the body to the cells. This may be triggered by a viral or other infection.

Elena Moltchanova, who led the study 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.”

Victoria King, research manager at the charity Diabetes UK said that previous studies had shown conflicting results, “but this larger study shows a stronger correlation which is interesting, especially as we still don’t know exactly why Type 1 diabetes develops.

“Investigating why we might be seeing this pattern could tell us more about what may be triggering the development of Type 1 diabetes”, she added. “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.”

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