Diabetes mellitus and hyperglycaemia are complex and common clinical problems that have serious adverse consequences for patient morbidity and mortality. In the past year, a body of revised guidelines and opinions has emerged from the South African, British, American and European diabetes authorities. An overview of these guidelines and position statements on diabetes mellitus in general, and perioperative hyperglycaemia, in particular, is offered. Perioperative hyperglycaemia is a very common problem, both because the actual incidence may be increasing worldwide, 2 and also because it describes a much wider problem than just diabetes mellitus.