This insulin B-chain peptide binds to a class II histocompatibility complex (MHC) allele called I-Ag7. A number of autoimmune diseases has been linked to class II proteins encoded by the MHC. Type 1 diabetes, or insulin-dependent diabetes mellitus, is a T cell-mediated disease that results in autoimmune destruction of pancreatic ß cells leading to hyperglycemia. This insulin B peptide may be a self-antigen candidate that could initiate the disease. Immunization with this peptide in mice led to autoantibodies and insulitis.