Non-ketotic Hyperglycemic Hemichorea in a Patient Newly Diagnosed With Diabetes: A Rare Neurological Manifestation of Uncontrolled Diabetes.

Non-ketotic hyperglycemic hemichorea-hemiballismus (NHH) is a rare but reversible movement disorder associated with poorly controlled diabetes mellitus. It is characterized by involuntary, non-suppressible choreiform, ballistic movements or several other involuntary movements (dystonia, tremors, etc), contralateral striatal hyperintensity on MRI, and hyperglycemia without ketosis. The exact pathophysiology remains unclear, but prompt glycemic control is essential for symptom resolution. We report the case of a 41-year-old man with no prior history of diabetes who presented with an acute onset of hemichorea affecting the left upper and lower limbs. Laboratory findings revealed hyperglycemia (18 mmol/L) with an elevated HbA1c (>12%), while brain MRI demonstrated characteristic T1 hyperintensity in the right basal ganglia. The patient was started on insulin therapy and oral antihyperglycemic agents, along with neuroleptics for symptomatic relief. By the third day of treatment, his movements began to improve. This case underscores the importance of recognizing NHH in patients with new-onset movement disorders, emphasizing the role of neuroimaging and early glycemic management for favorable outcomes.