Viral infections could play a role in the development of Type 1 diabetes, according to a review of existing studies.
Researchers found that people with diabetes are around nine times more likely to have had enterovirus than those without the condition. Enterovirus refers to a collection of viruses which can cause a range of symptoms, including fever, cold, rash, sickness and diarrhoea.
Experts from Sydney, Australia, reviewed 24 studies on the issue, involving more than 1,900 people with Type 1 diabetes, or a related condition known as pre-diabetes. Most of the participants were children, the time when Type 1 usually develops.
The researchers found a strong association between enterovirus and Type 1 diabetes.
While they said the findings "cannot prove" that enterovirus infection causes diabetes, the results provide "additional support to the direct evidence of enterovirus infection in pancreatic tissue of individuals with type 1 diabetes".
Writing in the British Medical Journal (BMJ), the authors concluded: "Our results show an association between Type 1 diabetes and enterovirus infection, with a more than nine times the risk of infection in cases of diabetes and three times the risk in children with autoimmunity.
"The odds of having an enterovirus infection in people with established diabetes suggest that persistent enterovirus infection is also common among patients with type 1 diabetes."
Type 1 diabetes is believed to be caused by a complex relationship between genetic factors, the immune system and the environment. Some 300,000 people in the UK have Type 1 diabetes.
The authors said genetics alone could not explain the rising numbers of people with the condition worldwide.
"In recent decades there has been a rapid rise in the incidence of childhood Type 1 diabetes worldwide, especially in those under the age of five," they said. "In Europe, from 1989-2003 the average annual increase was 3.9%, too fast to be accounted for by genetics alone."