The present study is a multicenter， randomized controlled clinical trial, which plans to enroll 450 diabetic patients aged more than 60 years. The participants will be randomly assigned in a 1:1 ratio and will receive either propofol or sevoflurane for intraoperative anesthesia maintenance to evaluate the impact of these two anesthetic drugs on postoperative delirium. The aim of our study is to explore whether the use of propofol for anesthesia maintenance in elderly diabetic patients undergoing elective non-cardiac major surgery can reduce the incidence of postoperative delirium. This study will provide new perspectives for improving perioperative management in elderly diabetic patients and optimizing anesthesia management strategies to reduce the risk of postoperative delirium.

Inclusion Criteria:

• Age ≥60 years
• Elective surgery (with an expected duration of 2 hours or more)
• ASA grade Ⅰ-Ⅲ
• Voluntary participation and informed consent obtained
• Diabetes mellitus

Exclusion Criteria:

• Pre-operative BMI≥35 kg/m² (Class II obesity or above)
• Severe hepatic dysfunction (Child-Pugh class C) or pre-operative dialysis-dependent renal dysfunction
• Known neurological or psychiatric diseases (Parkinson's disease, depression, schizophrenia), or cognitive impairment (dementia)
• Severe visual or auditory impairments, language barriers, or patients who cannot cooperate
• Long-term use of sedatives, antipsychotic drugs, or long-term alcohol abuse
• Neurosurgical patients
• Patients with a known allergy to the drugs used in this study or those suspected of having propofol infusion syndrome