Epidemiological and virological studies have established an association between some cases of insulin-dependent diabetes mellitus and certain viruses. The process leading to insulin-dependent diabetes mellitus is multifactorial and is dependent on the genetic make-up both of the virus and of the host. The best understood mechanism currently involves the coxsackieviruses for which a molecular mimicry between coxsackievirus P2-C protein and a protein on the beta cell membrane can lead to an autoimmune response that eventually destroys the beta cells.