An 83-year-old lady with type 2 diabetes mellitus was admitted to hospital with pneumonia. After 3 days of oral amoxicillin she developed ballism-choreiform movements of all four limbs. Her serum glucose and osmolality were raised. She had no factors suggestive of genetic or iatrogenic causes. A CT scan of the brain revealed bilateral putamen hyperintensities. She was started on tetrabenazine and subcutaneous insulin, which led to complete resolution of her symptoms.