Diabetes mellitus is a disease of antiquity with an estimated 20,000 people dying prematurely per year due to diabetes associated disease. Type 1 diabetes results from autoimmune destruction of insulin-producing pancreatic cells. Much effort has been dedicated to figure out the autoimmune background of this disease with a view to exploring how the immune system can be manipulated to prevent its occurrence. In this review, we explore the autoimmune basis of type I diabetes mellitus and equally the immune interventions that have been and are being employed to prevent type I diabetes mellitus.