A patient with type 1 diabetes mellitus and cerebellar ataxia associated with high titer of circulating anti-glutamic acid decarboxylase antibodies

A 66-year-old Japanese woman presenting with recent onset of type 1 diabete s mellitus and cerebellar ataxia was admitted to our hospital. Physical exa mination on admission revealed coordinate disturbance due to cerebellar ata xia, and the laboratory examination showed marked hyperglycemia with ketosi s and impaired insulin secretion. Anti-glutamic acid decarboxylase (GAD) an tibodies in high titer were detected in patient's serum. Immunoblotting sho wed the patient's serum reacted with a 65 kDa protein in tissue extracts fr om rat pancreas and cerebellum, and immunohistochemical study produced posi tive immunostaining in the pancreatic islets of Langerhans, the axons of Pu rkinje cells and the nerve terminals in the granular layers of cerebellum o f the rat. This is the first case presenting with concomitant type 1 diabet es and cerebellar ataxi associated with high titers of circulating anti-CAD antibodies which may play a critical role in the development of the diseas es.