Type 1 diabetes mellitus and autoimmune cerebellar ataxia with anti-glutamate decarboxylase

The cerebellar ataxia variant associated with antibodies against glutamic acid decarboxylase 65 (GAD-Ab) is associated with type 1 diabetes mellitus (DM). We present the case of a 63-year-old woman with cerebellar ataxia of unknown origin, who was later diagnosed with T1DM. The identification of GAD-Ab in the cerebrospinal fluid (CSF) demonstrated the association between the two conditions. Diagnosis requires demonstration of increased intrathecal synthesis of GAD-Ab. We emphasize the importance of considering GAD-Ab-associated cerebellar ataxia among the causes of cerebellar ataxia to provide timely and effective treatment.