Abstract: AIM: To compare the duration of 0.25%ropivacaine used for sciatic nerve block between type 2 diabetic patients and non-diabetic patients, and to explore the factors affecting the duration of nerve block.  METHODS: Sixty eight patients with unilateral lateral malleolus fracture who were to be treated with open reduction and internal fixation were selected from January 2021 to January 2022, aged 20-80 years old, ASA I-III, including 28 diabetic patients and 40 non-diabetic patients. All patients were given 0.25%ropivacaine 20 mL to the superior popliteal sciatic nerve under the guidance of ultrasound. The onset and duration of sensory block were evaluated by blunt needle stimulation. The onset and duration of motor block were evaluated by dorsiflexion and plantar flexion of the operated foot. The interval between the end of the operation and the patient's first request for analgesia was taken as the duration of nerve block analgesia. RESULTS: Compared with non-diabetic patients, the duration of sciatic nerve sensation, motor block and analgesia in diabetic patients were prolonged (P<0.05). There was no significant difference in the onset time of sciatic nerve sensation and motor block between the two groups (P>0.05). Linear regression analysis showed that diabetes mellitus, duration of diabetes mellitus, fasting blood glucose and glycosylated hemoglobin were factors affecting the duration of nerve block, and fasting blood glucose was not related to the duration of analgesia. CONCLUSION: 0.25%ropivacaine can prolong the duration of sciatic nerve block in diabetic patients. The duration of diabetes, diabetes, fasting blood glucose and glycosylated hemoglobin are positively correlated with the duration of block.

Key words: type 2 diabetes mellitus, ropivacaine, sciatic nerve, nerve block