BACKGROUND: Chorea can be caused by a variety of diseases, including neurodegenerative disorders, vascular events, toxic-metabolic states, and immunologic and infectious diseases. We describe a patient who presented with hemichorea as the initial manifestation of Diabetes Mellitus (DM) and responded partially to the glycemic control. CASE REPORT: A 63-year-old, healthy Hispanic man with no prior history of medical illness presented with subacute onset, gradually progressive hemichorea of 6 weeks' duration. On evaluation, he was found to have non-ketotic hyperglycemia with high serum glucose (328 mg/dL), elevated hemoglobin A1C (9.9%), and absent ketones. Magnetic Resonance Imaging of the brain demonstrated hyper intense signals in bilateral basal ganglia on T1W images. He was diagnosed to have DM. Despite optimal glycemic control with insulin, the patient continued to have hemichorea at 3 months follow-up and required haloperidol for control of the involuntary movements. SIGNIFICANCE: Involuntary movements, particularly hemichorea, can be a manifestation and rarely be a presenting sign of DM.