The finding could help explain a dramatic rise in diabetes incidence among very young children, and could even lead to better ways to prevent and treat the disease, researchers say.
The analysis of 26 studies published today in the journal BMJ Online First revealed that children with type 1 diabetes are almost 10 times more likely to show signs of enterovirus infection than children without the disease.
Enteroviruses are the second leading viral cause of cold-like symptoms in children, after rhinoviruses.
Enteroviruses and Type 1 Diabetes
Researchers have long believed that genetic predisposition, the immune system, and environmental triggers interact to cause type 1 diabetes, a disease that affects nearly one in 400 children and adolescents in the U.S., according to the American Diabetes Association.
Enteroviruses have been on the radar as a possible disease trigger for decades. While some studies have found evidence of a link, others have not.
The newly published analysis was the first to combine results from molecular enterovirus-diabetes studies, and the findings were clear, says researcher Maria E. Craig, PhD, of the University of New South Wales in Sydney, Australia.
“We saw a very strong association between enterovirus infection and type 1 diabetes," Craig tells WebMD. “Obviously studies like the ones we looked at cannot prove cause and effect, but the findings make a strong case for this association.”
Since enteroviruses are made up of ribonucleic acid (RNA) and proteins, the studies included in the analysis measured RNA or protein in the blood, stool, or tissues of type 1 diabetic or pre-diabetic patients and compared them with people who did not have the disease.
Children with type 1 diabetes were 9.8 times more likely to be infected with enterovirus than children without the disease and those with pre-diabetes were three times more likely to have the infection than other children.
The Search for a Type 1 Vaccine
The next step, Craig says, is identifying the specific enterovirus or viruses associated with type 1 diabetes, with the goal of developing a vaccine to prevent type 1 diabetes.
“There are more than 100 strains of enteroviruses, but probably only a handful are associated with type 1 diabetes,” she says.
Virologist Didier Hober, MD, PhD, of France’s University Lille says other important questions remain about enteroviruses and type 1 diabetes, such as whether the virus is involved in all or just some cases of the disease.
He says patients who tested negative for the virus in past studies may have actually had the infection at levels that were too low to detect.
Hober says the enterovirus connection may also explain the dramatic rise in type 1 diabetes in higher-income countries like the U.S. and European countries.
The thinking is that improved hygiene has left babies more vulnerable to assaults from viruses like enterovirus because mothers today pass on fewer protective antibodies than were passed on by past generations of mothers.
If enteroviruses play a big role in type 1 diabetes, the so-called "hygiene hypothesis" could explain why disease rates have not risen in poorer, less industrialized countries, he tells WebMD.
Looking for Other Diabetes Triggers
While enteroviruses may prove to be an important environmental trigger for type 1 diabetes, it is not likely to be the only one, Seattle endocrinologist William Hagopian, MD, PhD, tells WebMD.
Very early exposure to cow’s milk and early exposure to gluten have also been linked to type 1 diabetes in some studies.
Hagopian is leading a study sponsored by the National Institutes of Health that will closely follow a large group of high-risk newborns from the U.S., Finland, Germany, and Sweden through childhood and into early adulthood in an effort to determine if these environmental exposures or others play a role in type 1 diabetes.
“We are going to cast a very large net in an effort to identify the triggers that lead to this disease,” he tells WebMD. “We will be looking at the potential triggers that have been on our radar, and we will also be looking for those we may not know about.”