Diabetes mellitus due to autoimmune destruction of the insulin-producing pancreatic islet cells. The prevalence of type 1 diabetes appears to be approximately 0.12% of the U.S. population. This prevalence is a far smaller number than that for type 2. In autoimmune disease, the insulin- producing pancreatic islet cell is destroyed because the immune system has sensed the presence of an antigen that it recognizes, not as a self-made protein, but as a foreign protein. It then destroys this protein. The interleukins are involved in the autoimmune process and so too is apoptosis.