Postoperative neurocognitive disorders (PND) are common postoperative complication of central nervous system, leading to increased risk of the working ability loss after surgery, longer hospital stay, increased medical costs and increased surgical mortality. It is classified as perioperative neurocognitive disorders in mental disorders.Aging is an important demographic characteristic in China, and the elderly is also a population susceptible to PND. There is a lack of targeted prevention and control measures for PND. Central insulin resistance is an important mechanism of cognitive impairment in elderly patients, and exogenous supply of central insulin may be an important measure to improve PND. Compared with conventional subcutaneous and intravenous supply, intranasal insulin administration not only has little effect on blood glucose and insulin levels, but also enters the center through the blood-brain barrier easily and efficiently. Long-term use of intranasal insulin can improve the cognitive function of chronic diseases, but there is a lack of clinical studies on improving PND by intranasal insulin. This study will verify the effectiveness of intranasal insulin in the PND improvement of elderly patients.

This study is intended to carry out a large sample, multicenter, double-blind, randomized, placebo, and controlled clinical study. Elderly non diabetes patients undergoing elective extrathoracic, breast, orthopedic, urinary, abdominal, and gynecological operations under general anesthesia are included. They are randomly divided into intranasal insulin group or saline group. Before anesthesia induction, they are given the first nasal spray, once per hour, 20 IU insulin or equal volume saline each time until the end of the operation. Follow up 1 day before operation, 1-7 days after operation, 30 days and 12 months respectively, and evaluate cognition with relevant scales. To verify that compared with the same volume of saline, intranasal insulin can reduce the incidence of postoperative delirium, the incidence of PND 1 year after surgery, and the related cognitive quantitative indicators of ApoE- ɛ4 Gene susceptibility, intraoperative EEG parameters, NfL, IL-6, IL-10, CRP and other biochemical indicators were used to explore the mechanism of intranasal insulin to improve PND.

Inclusion Criteria:

• Patients under general anesthesia through oral intubation;
• Patients undergoing elective extrathoracic, breast, orthopaedic, urological, abdominal and gynecological operations;
• Age ≥ 65 years;
• Cardiac function grade I~II (NYHA standard), ASA grade I~III;
• Volunteer for anticipating study and sign an informed consent form;

Exclusion Criteria:

• Diabetes patients;
• Previous history of craniocerebral and spinal cord trauma, surgery, stroke, and inability to place electrodes on the head;
• History of nasal cavity stuffiness, epistaxis, rhinitis, and nasopharynx surgery; The operation position is prone and it is difficult to implement intranasal administration;
• Those who cannot cooperate with the assessment of the scale or have delirium before operation;
• Preoperative fasting blood glucose<4 mmol/L;
• Those who have participated in other clinical trials.

The research plan will not be made public until the research results are published