Non-ketotic Hyperglycemic Hemichorea as a Clue to Undiagnosed Type 2 Diabetes Mellitus in an Elderly Man: A Case Report

Non‑ketotic hyperglycemic hemichorea is a rare neurologic complication associated with poorly controlled and, in exceptional cases, previously undiagnosed type 2 diabetes, characterized by sudden unilateral choreiform movements and basal ganglia hyperdensity on CT or T1-hyperintensity on MRI. We report the case of a 76‑year‑old male without routine primary-care follow-up who presented to the emergency department after one week of left-arm choreo‑dystonic movements, accompanied by mild left-sided hemiparesis and hypoesthesia. Laboratory evaluation revealed severe hyperglycemia (381 mg/dl) and glycosuria but no ketonuria. Non-contrast brain CT identified a discrete hyperdensity in the right caudate and lentiform nucleus, with no additional findings to suggest hemorrhagic or ischemic stroke. A 6-unit intravenous bolus of regular human insulin normalized serum glucose and markedly reduced neurological symptoms. These findings were consistent with non‑ketotic hyperglycemic hemichorea. Following complete resolution of hemichorea at discharge, the patient underwent glycemic optimization with insulin and oral antidiabetic agents, achieving HbA1c normalization within seven months and transitioning to primary care follow-up without recurrence of neurological symptoms. This case highlights hemichorea as a possible initial manifestation of undiagnosed diabetes, especially in an elderly man, and underscores the need for systematic metabolic screening in primary-care settings to facilitate early diagnosis and prevent such atypical presentations.