Insulin autoimmunity associated with vitiligo: a rare case presentation.

Summary: Insulin autoantibody syndrome (IAS) or Hirata's disease is a rare condition characterized by recurrent fasting hypoglycaemic and postprandial hyperglycaemic episodes. Insulin autoantibodies are diagnostic for the condition. Hirata's disease has been seen to be associated with other autoimmune conditions. Vitiligo is a common depigmentation disorder whose exact cause is unknown but thought to have an autoimmune aetiology. Although autoimmunity plays a role in the pathogenesis of both the diseases, association between the two has not been reported till date. In our case, a 72-year-old Indian woman with vitiligo for the past 30 years presented with recurrent episodes of fasting hypoglycaemia. She was found to have very high levels of fasting insulin, C-peptide, and insulin antibody and was diagnosed with IAS. Thus, we conclude that the clinical spectrum of Hirata's disease has to be taken as more heterogenous than previously assumed.

Learning points: Insulin autoantibody syndrome (IAS) or Hirata's disease is a rare condition characterized by recurrent fasting hypoglycaemic and postprandial hyperglycaemic episodes in which insulin plays a major role. Insulin autoantibodies are diagnostic for IAS. The endocrine insulin and its autoantibodies play a major role in the pathogenesis of the disease. Vitiligo is a common depigmentation disorder whose exact cause is unknown but thought to have an autoimmune aetiology. IAS and vitiligo are two diseases with autoimmune aetiology which has been seen to be associated with each other (the first case to be reported). The clinical spectrum of Hirata's disease has to be taken as more heterogenous than previously assumed. On dealing with autoimmune diseases, we should also keep in mind about other diseases with autoimmune pathogenesis.