The incidence of diabetes is rising rapidly and individuals with the condition often have complex comorbidities, which may increase the need for surgical procedures such as amputation and cardiac, renal and eye surgery. Patients with diabetes undergoing surgery may have specific needs, particularly in relation to blood glucose control, and healthcare professionals need to be able to assess and manage these individuals to ensure optimum surgical outcomes. This article considers the potential effects of anaesthesia and surgery on blood glucose control. Diabetes-related complications, particularly signs and symptoms, and effects of these complications on patient safety during surgery are discussed. Specific pre and post-operative care of patients with type 1 and type 2 diabetes is described, with reference to nil-by-mouth practices, blood glucose control, and post-operative infection and pain.