Type 1 diabetes has been on the rise worldwide, but in Australia, the problem appears to be turning around at last.

For the first time since 1980, the number of young Australian children diagnosed with this autoimmune condition has begun to slow, and it could have something to do with the country's impressive immunisation program.

New research has shown Australia's curious decline in type 1 diabetes began immediately after the introduction of the oral rotavirus vaccine, encouraging a hunch that has existed for some 20 years.

"While not conclusive, our latest study suggests that preventing rotavirus infection in Australian infants by vaccination might also reduce the risk of type 1 diabetes in some infants at genetic risk," says senior author Len Harrison, a physician and researcher in molecular medicine at the University of Melbourne.

This curious correlation was first discovered by the team of researchers just before the turn of the century, when they noticed that the immune markers in type 1 dabetes (T1D) looked remarkably similar to the rotavirus (RV) infection.

Since then, scientists have found that the RV infection can trigger an immune attack on insulin-producing pancreatic cells, the organ responsible for controlling a person's sugar levels and a key player in diabetes.

When the two oral RV vaccines were introduced into Australia's national immunisation program in 2007, it presented a ripe opportunity for further research.

Using publicly available data, the researchers compared the incidence of type 1 diabetes eight years before and eight years after this change..

The findings suggest that the RV virus might do more than we thought. This vaccine alone has the potential to save millions of young children worldwide from a severe and potentially life-threatening form of diarrhoea. Could it also be keeping the development of T1D at bay?

It's certainly a possibility. In the years after Australia introduced the RV vaccine program - a time when national coverage was estimated at 84 percent - the incidence of T1D decreased by 14 percent among children aged 0 to 4.

"The significant decrease... wasn't seen in older children aged 5-14," explains lead author Kirsten Perrett, an expert in immunisation and allergies at the University of Melbourne.

"This suggests the young children could have been exposed to a protective factor that didn't impact older children."

While this doesn't necessarily mean the RV vaccine is putting a stop to this incurable disease, it does build on previous research that suggests the rotavirus infection may be a risk factor for diabetes.

At least, in Australia it might be. For some reason, a study in Finland using a smaller sample size and shorter time span didn't find the same correlation, although it could have something to do with genetic and environmental differences between the two countries.

Armed with a promising lead, researchers in Australia are continuing to dig through the national data, hoping to find more clues that can link these two conditions.

"At this stage, we don't yet know whether the reduction in type 1 diabetes is a permanent effect, or transient, and it may only be relevant to Australian children," says Harrison.

The take away message? Vaccinate, vaccinate, vaccinate. You never know what extra good it might do.

This study has been published in JAMA Pediatrics.