Researchers at the Walter and Eliza Hall Institute of Medical Research say the vaccine involves those at risk of the disease taking insulin through a nasal spray.

Professor Len Harrison, said it would eventually be possible to screen babies at birth, then determine at-risk babies and could give them the vaccine early to stop the disease process starting.

Unlike type 2 diabetes, which is related to lifestyle and diet, type 1 is an auto-immune disease. In type 1 diabetes, the body's immune system reacts against the insulin within the eyelet cells of the pancreas, and eventually the cells stop producing insulin.

Prof Harrison has devised a test to detect children and young adults in the early stages of the disease. He said the insulin in the nasal spray could stop the type 1 rogue immune response and trigger a healthy response.

"That good immune response . . . will block the kind of immune response that would cause destruction of insulin-producing cells," he said.

A five-year trial involving 38 children at Royal Melbourne Hospital and the Hall Institute proved the vaccine protected against the development of diabetes. Of the 38 children, 12 who began with very little or no insulin-producing function went on to develop diabetes within one or two years. None of the 26 who began the trial while still producing some of their own insulin developed diabetes.

"We are very excited because we think it's a very significant step towards prevention of type 1 diabetes," Prof Harrison said. "It's likely it won't totally prevent diabetes in humans who have this treatment. But even if it . . . delays the onset even just a few years, it would be significant."

The cost of treating someone who is a newly diagnosed diabetic is at least $5000 a year.

An onset delay would reduce the risk of complications that cut life expectancy by 15 years. These include heart disease, kidney failure, blindness and amputation.

It is not known how long the vaccine lasts. Prof Harrison said it was likely to be effective for months, but more trials were needed. All we know in the trial is that it was safe, and that it induced changes in the immune system consistent with protection, but in order to prove that, we have to, and we are now going to this much larger multi-centre trial with many more children, three doses, to prove that it definitively prevents the development of diabetes.
Participants in the trial, which began in 1997, had weekly doses of nasal insulin vaccine and blood tests every month for the first year.

"When we measured the ability of these children to make insulin every six months we were pleasantly surprised . . . all the children who started out with normal ability to make insulin remained stable," Prof Harrison said.

He hoped his model of immune regulation could be used to treat or prevent other auto-immune diseases such as multiple sclerosis and rheumatoid arthritis. Prof Harrison is now preparing for an international trial.