Insulin-dependent diabetes mellitus (IDDM) is a serious disorder comprising approximately 10% of the total diabetic population. The majority of the genetic mutations that result in the phenotypic expression of the IDDM genotype are in the immune system. In some, the disease arises as a consequence of a viral infection. While some viruses target the islet beta cell and destroy it, other viruses induce changes in the antigen recognition system such that the affected individual appears to have autoimmune disease. Autoimmune-IDDM results from one or more mutations in the immune system that result in a failure to distinguish self antigens from foreign antigens. As a result, the beta cells of the endocrine pancreas are destroyed. This review addresses the issue of whether dietary factors, in particular, milk protein, can initiate the autoimmune process. Based on the population studies available in the literature, the conclusion is reached that, while antibodies to milk proteins can be found in the patient with autoimmune diabetes mellitus, these antibodies were probably elicited by a closely related protein (antigen mimicry). Because one of the features of autoimmune disease is a loss of antibody specificity, cross-reactivity occurs and appears to identify milk protein(s) as the antigen.