Type 1 diabetes is an autoimmune disease in which the patient's immune system destroys the insulin-secreting beta-cells in the pancreatic islets of Langerhans. A majority of cases is thought to occur as a result of gene-environment interactions. The identity of the environmental factors remains unknown mainly because of the difficulty in linking past exposures with later disease development. Overall, the data suggest a model in which individuals develop diabetes by several different pathways, each influenced by numerous genetic and environmental variables. The most investigated environmental factors are diet and viruses. In this review, we examine the evidence that the source of dietary proteins can modify diabetes outcome, describe new approaches to identify candidate diabetes-related dietary agents, examine possible links with gut dysfunction, discuss some of the limitations, and propose a multifactorial model for dietary modification of diabetes. The key to diabetes pathogenesis, its prevention, and the ultimate success of beta-cell replacement therapies lies in understanding how the environment controls disease expression. Dietary proteins could be one of these keys.