Extensive data have shown that acute hyperglycemia is commonly present in the perioperative period among patients undergoing surgery or with critical illness, and a direct relationship between perioperative hyperglycemia and mortality has been established. An outstanding trial by Van den Berghe showed that intensive insulin therapy (IIT) (target blood glucose, 80-110 mg/dL) reduced in-hospital mortality. However, recent large trials have questioned the efficacy and safety of IIT and raised concerns about increased mortality rates due to hypoglycemia. This review focused on how anesthetic agents and techniques, fluid management and preoperative oral intake would affect glucose metabolism and insulin resistance, in addition to recent controversial effects of IIT on improved mortality rate. Anesthesiologists should pay attention not only to the efficacy and risks of IIT during the perioperative period, but also to effects of fluid management, anesthetic agents and techniques during anesthesia on glucose homeostasis.