Type 1 diabetes could be prevented by a new nasal insulin vaccine

A world-leading medical trial conducted in Melbourne suggests that the onset of type 1 diabetes could be prevented in many at-risk people by a new nasal insulin vaccine.

A team led by Professor Len Harrison, from The Walter and Eliza Hall Institute of Medical Research, conducted the phase 2 trial at The Royal Melbourne Hospital in children at high risk of developing type 1 diabetes. Of the 38 children in the trial, 12 who started with very little or no insulin-producing function went on to develop diabetes within one to two years. However, of the other 26, all of whom began the trial with some of their own insulin-producing function, none developed diabetes after three years.

Commenting on the trial, Professor Harrison said, "Type 1 diabetes is an autoimmune disease in which the body's own immune system mistakes 'self' as being a 'non-self' invader and mounts an attack against healthy tissue. In type 1 diabetes, 'self' is actually the hormone insulin in the beta cells of the pancreas. The guardian immune cells of the body, the killer T cells, attack the insulin-producing beta cells, leading to a lack of insulin. Without insulin, which normally controls the level of glucose in the body, the level of the hormone in the bloodstream increases abnormally. The consequence, diabetes, can result in disastrous complications: kidney failure, blindness, nerve damage, amputation, heart attack and stroke.

"Our objective is to re-educate the immune system to prevent or greatly reduce the possibility that it could mistakenly attack insulin. We do this by delivering insulin to the mucous membranes, an area of the body where the immune reaction to proteins like insulin is protective and blocks the killer T cells. We showed this first in mice that develop type 1 diabetes, before proceeding to the trial of intranasal insulin in humans.

"The results from the trial are very encouraging. First, the use of nasal insulin has been established as being safe. Second, we found that nasal insulin issued protective instructions to the immune system in humans, as we found in the mice that were protected from diabetes by this treatment. The hope is that these instructions will stop the self-destructive process in people at risk of developing type 1 diabetes.

"We are now in final preparations for a further trial in a larger group of at-risk children and young adults. This will use several doses of nasal insulin to determine the best outcome.

"Currently, at least 100,000 Australians suffer from type 1 diabetes.  The incidence of the disease has increased, especially in younger children. In addition, we are discovering that some adults with diabetes have a less dramatic form of type 1 diabetes. A safe vaccine like intranasal insulin could reduce the risk of type 1 diabetes and its huge personal, social and economic costs."

The nasal insulin trial was conducted with the support of the NH&MRC and the Juvenile Diabetes Research Foundation International (JDRFI), the leading charitable fund source and advocate of type 1 diabetes research worldwide.

The findings of the nasal insulin trial are published in DiabetesCare, a journal of the American Diabetes Association, vol 27, no 10, October 2004.

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