Patients without diabetes who have surgery often develop elevated blood glucose levels. This article describes the effects of stress on blood glucose levels and the importance of treating stress-induced hyperglycaemia in surgical patients. It suggests that all patients with or without diabetes could benefit from the maintenance of strict blood glucose control within set parameters during and after surgery. The evidence suggests that strict control of blood glucose levels and frequent monitoring and maintenance of normoglycaemia may reduce post-operative complications and promote better patient long-term outcomes. The use of intensive insulin therapy is recommended for all post-operative patients in intensive care.