Hemichorea-hemiballismus, secondary to hyperglycemia, is a rare but easily treatable condition that is usually associated with type II diabetes mellitus. This is a case of a 68- year lady, with long-standing, poorly controlled diabetes mellitus, who presented with disabling right-sided hemichorea-hemiballismus. The T1-weighted magnetic resonance imaging revealed hyperintensity in the basal ganglia. The abnormal movements subsided within a few days after achieving euglycaemia with insulin therapy. This case highlights the importance of treatment of hyperglycaemia in a diabetic patient presenting with acute or sub-acute abnormal movement disorder. Key Words: Hemichorea, Hemiballismus, Hyperglycemia, T-1 hyperintensity.