<P> One theory proposes that type 1 diabetes is a virus - triggered autoimmune response in which the immune system attacks virus - infected cells along with the beta cells in the pancreas . Several viruses have been implicated, including enteroviruses (especially coxsackievirus B), cytomegalovirus, Epstein--Barr virus, mumps virus, rubella virus and rotavirus, but to date there is no stringent evidence to support this hypothesis in humans . A 2011 systematic review and meta - analysis showed an association between enterovirus infections and type 1 diabetes, but other studies have shown that, rather than triggering an autoimmune process, enterovirus infections, as coxsackievirus B, could protect against onset and development of type 1 diabetes . </P> <P> Pluripotent stem cells can be used to generate beta cells but previously these cells did not function as well as normal beta cells . In 2014 more mature beta cells were produced which released insulin in response to blood sugar when transplanted into mice . Before these techniques can be used in humans more evidence of safety and effectiveness is needed . </P> <P> Vaccines to treat or prevent Type 1 diabetes are designed to induce immune tolerance to insulin or pancreatic beta cells . While Phase II clinical trials of a vaccine containing alum and recombinant GAD65, an autoantigen involved in type 1 diabetes, were promising, as of 2014 Phase III had failed . As of 2014, other approaches, such as a DNA vaccine encoding proinsulin and a peptide fragment of insulin, were in early clinical development . </P>

Mechanism of type 1 and 2 diabetes mellitus