A specific virus family has been implicated in the development of Type 1 diabetes, raising the prospect of vaccinations against the disease.
Data from two studies show a clear link between the condition and group B coxsackieviruses, which are known to damage insulin-producing cells in the pancreas.
Type 1 diabetes is an autoimmune disease caused by the body's defences destroying insulin-producing beta cells.
But what triggers the extreme immune reaction in the first place has been an unanswered question.
Suspicion has fallen on enteroviruses, one of the most common infective agents in humans. They include the virus responsible for the common cold, as well as those responsible for polio and viral meningitis.
The new study narrowed the diabetes culprit down to one particular enterovirus population known as group B coxsackieviruses.
A similar association was not seen between 35 other enterovirus types and Type 1 diabetes.
Researchers looked at data from two studies. One, the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) study, followed children at genetic risk for Type 1 diabetes from birth to 15 years of age. The other, VirDiab, included children with newly diagnosed diabetes from five European countries.
The findings, from a team led by Professor Heikki Hyoty, from the University of Tampere in Finland, appear in the journal Diabetes.
Karen Addington, chief executive of the Type 1 diabetes charity JDRF, which funded the research, said: "Here we have two major studies, independently done, both indicating that particular viruses could have some role in triggering Type 1 diabetes in children with a high genetic risk of the condition.
"The next step is that causation, rather than correlation, needs to be established behind the fact that these children with Type 1 diabetes also had these viruses. This could take considerable time. But if achieved, it may be that with screening and a vaccine for the viruses, we can prevent a proportion of Type 1 diabetes incidences.
"Achieving prevention of an autoimmune condition in this way would be historic."
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Type 1 diabetes affects around 400,000 people in the UK, 29,000 of whom are children.
Unlike Type 2 diabetes, which is far more common, the disease is not related to lifestyle and obesity. Sufferers cannot make their own insulin and have to inject themselves with the hormone to control their blood sugar and stay alive.
The DIPP study found that children with signs of the autoimmune reaction underlying Type 1 diabetes were 50% more likely to have antibodies against Group B coxsackieviruses.
In the VirDiab study, the viruses increased the chances of children being newly diagnosed with Type 1 diabetes by 70%.