Surgery induces a 'stress' state leading to post-operative hyperglycaemia. To investigate this effect on patients with Type 2 Diabetes Mellitus, we reviewed the records of 50 diabetic patients who underwent surgery without intra- operative insulin. Demographic features together with pre-operative and post-operative blood glucose readings were noted, 27.3% of patients with well controlled pre-operative blood glucose levels developed post-operative hyperglycaemia. In contrast, 84.6% of patients with poorly controlled levels developed the same. Poor control of blood glucose and duration of operation were the only significant predictors of post-operative hyperglycaemia.