Perioperative hyperglycemia can increase surgical complications morbidity and patients' mortality, which is closely related to prognosis. The application of intensive insulin trerapy (IIT) during the perioperative period can control blood glucose levels well, reduces infection， and improves prognosis, while high controversy about its use exists. In order to optimize blood glucose regulation and to improve the prognosis of patients, this article proposed to explore the mechanism of perioperative hyperglycemia, the effects of IIT application on blood glucose level, the perioperative infection control， and the prognosis of patients.