Hemichorea-hemiballism (HCHB) associated with nonketotic hyperglycemia is the most common cause of unilateral chorea in patients with type 2 diabetes mellitus. T1-weighted MRI characteristically demonstrates hyperintensity in the contralateral corpus striatum. Here we describe a case of HCHB associated with nonketotic hyperglycemia and unusual brain involvement. A 51-year-old man presented with involuntary limb movements for several months. He had a history of diabetes mellitus and poorly controlled hyperglycemia. MRI demonstrated characteristic striatal hyperintensity, with involvement of the temporal lobe and midbrain. The patient's hyperglycemia was controlled with medication. However, his involuntary movements were reduced in terms of severity, but not eliminated, by the time of discharge. HCHB associated with hyperglycemia usually resolves rapidly after correction of blood glucose levels; thus, early recognition and glycemic control are needed to prevent an irreversible outcome.