Optimal Dose of Intranasal Insulin Administration for Reducing Postoperative Delirium Incidence in Older Patients Undergoing Hip Fracture Surgery

Objectives: To investigate the effects of administration of different intranasal insulin doses on postoperative delirium (POD) incidence in older patients with trolled trial (23K214-001, NCT06443957). Setting: The First Hospital of Jilin University from July 2023 to February 2024. Patients: Patients aged >= 65 years with hip fractures scheduled for elective unilateral hip arthroplasty or closed reduction and intramedullary nailing under spinal anesthesia. Interventions: Patients were randomly divided into a Control group (n = 43, 1 ml normal saline administered intranasally) or I-20 group (n = 45, 1ml 20U/ml insulin administered intranasally) or I-40 group (n = 42, 1ml 40U/ml insulin administered intranasally). Measurements: POD incidence within postoperative days 1-3 was recorded. Fingertip blood glucose levels were recorded 40 min after insulin or saline administration the day before surgery, operating room entry and immediately after the procedure. Cerebrospinal fluid (CSF) glucose and lactate levels were also measured. Results: Compared with the Control group, the I-20 and I-40 groups showed significantly lower POD incidence (39.5% versus 11.4% versus 14.3%, p = 0.002). Furthermore, no significant difference in POD incidence was observed between the I-20 and I-40 groups. CSF glucose levels were significantly higher in the I-40 group than in the Control group (p <0.0167). CSF lactate and fingertip blood glucose levels were not significantly different among the groups. Conclusion: Intranasal insulin administration at doses of 20U and 40U effectively reduces the incidence of POD in older patients with