Introduction: Chorea, hyperglycemia, basal ganglia syndrome (CHBG) is a rare neurological complication of non-ketotic hyperglycemia which occurs more often in elderly female patients with undiagnosed or poorly controlled diabetes mellitus. Case report: We present the case of a 82-year old female, diagnosed with type 2 diabetes mellitus, but untreated, admitted with non-ketotic hyperglycemia and hemiballistic movements in her left limbs, with acute onset, that changed to choreic movements and then disappeared. Brain magnetic resonance imaging (MRI) showed characteristic hyper intensity in the right (contralateral) putamen on the T1-weighted images. Other secondary causes for ballismus and chorea were excluded. Hemiballismus/hemichorea non-ketotic hyperglycemic basal ganglia (CHBG) syndrome was considered and blood glucose was lowered using insulin. As symptomatic treatment, Haloperidol was started but, due to adverse effects, it was stopped and Clonazepam was associated. The movement disorders disappeared in two weeks after glycemic control. Significance: Movement disorders, like chorea and/or ballismus (hemichorea/hemiballismus) can be a marker of uncontrolled known diabetes mellitus or a presenting sign for an undiagnosed diabetes mellitus. The chorea hyperglycemia basal ganglia (CHBG) syndrome is rare and likely undiagnosed but, being aware of it’s existence is of high importance, as normalising blood sugar values severe neurological complications can be avoided.