BACKGROUND: Postoperative metabolic disorders and inflammatory responses are closely associated with postoperative delirium (POD). Preoperative oral carbohydrate intake can alleviate postoperative insulin resistance and the inflammatory response. This study aimed to evaluate the effects of preoperative oral carbohydrate intake on the incidence of POD in older patients undergoing lower limb orthopedic surgery. METHODS: Eighty patients were randomly assigned to oral intake of 200 mL carbohydrate solution (Group CHO) 2 h before surgery or fasting for 8 h before surgery (Group C). The primary outcome was the incidence of POD. Fasting plasma glucose, interleukin (IL)-6, and C-reactive protein (CRP) levels were assessed before surgery and 1, 3, and 5 days after surgery (D1, D3, and D5). RESULTS: The incidence of POD in Group CHO was lower than that in Group C (P = 0.005). Blood glucose, IL-6 and CRP levels of Group CHO were significantly lower than those of Group C on D1 and D3 (P <
0.05). CONCLUSIONS: Preoperative oral carbohydrate intake can reduce the incidence of POD in older patients by ameliorating postoperative metabolic disorders and reducing inflammatory responses. TRIAL REGISTRATION: ChiCTR2300070154, Date of registration: 03/04/2023.