Hemichorea associated with hyperglycemia is very rare disease. Furthermore, hemichorea as the initial manifestation of diabetic mellitus is extremely rare. We here report the case of new-onset hemichorea as first manifestation of type 2 diabetes mellitus. A 82-year old male without previously diagnosed diabetes mellitus, had visited at outpatients department of neurology because of dyskinesia at left side for 3 days. At initial studies, high signal basal ganglia lesion on the T1-weighted brain Magnetic Resonance Imaging and non-ketotic hyperglycemia were noted. Hemichorea had not improved by haloperidol monotherapy but by glycemic control. After insulin therapy, patient’s capillary blood sugar was controlled and hemichorea disappeared without anticonvulsants therapy