We report a patient with hyperosmolar non-ketotic hyperglycaemia who presented with chorea and septic arthritis on his knee. The chorea resolved completely and quickly with correction of the metabolic disturbance, only to return just as quickly when his metabolic disturbance subsequently deteriorated as a result of overwhelming septicaemia, suggesting coexisting cerebral ischaemia, although the basis of focal neurological sign in non-ketotic hyperglycaemia remains controversial.