What causes type 1 diabetes?

By the time a person with type 1 diabetes experiences symptoms, almost all the beta cells in the pancreas have been destroyed. This destruction is almost certainly as a result of an autoimmune process in which the body produces antibodies to its own cells. However, the details of the process are not clear.

It seems that there must initially be a genetic tendency for the disease, which is then triggered by an environmental event such as a viral infection. The third step in the process is inflammation of the pancreas called insulitis. The fourth step is an alteration in the surface of the beta cell so that it is no longer recognised as “self” (part of the body) but is perceived by the immune system as a foreign cell or “non-self”. The fifth step is the development of an immune response.

The end result is the destruction of the beta cell and the development of diabetes.