Hemichorea-hemiballism associated with non-ketotic hyperglycaemia is a rare dyskinetic syndrome during uncontrolled or undiagnosed diabetes. We reported a 41-year-old man suffering from sudden choreodystonic movements and undiagnosed hyperglycaemia. We described a combination of several rare aspects, emphasising the importance of screening for diabetes as a cause of acute onset of hyperkinetic movement disorders.