Objective To observe the clinical efficacy of iRoot SP single ⁃tip filling for diabetic patients complicated with chronic apical inflammation. Methods Eighty diabetic patients complicated with chronic apical inflammation were selected and divided into two groups according to root canal filling procedure. The observation group（n = 40）was treated with iRoot SP single⁃cone obturation，and the control group（n = 40）was treated with warm gutta ⁃percha vertical condensation with AH Plus sealer. The two groups were followed up and compared for emergency reactions within 1 week after root canal filling and the clinical efficacy at 3 months and 1 year after obtu⁃ ration. Results Significant differences in the degree of emergency reactions within 1 week after obturation was noted（Z = 2.806，P = 0.037），which were lower in the observation group than in the control group. No statistically significant difference in the efficacy rate between the two groups at 3 months and 1 year after operation was found （χ2 = 0.000，P = 1.000）；There was a significant difference in clinical efficacy between the two groups at 3 months after obturation（Z = 2.269，P = 0.023），and the cure rate of the observation group was higher than that of the control group. However，no significant difference in clinical efficacy between the two groups at 1 year after operation was found（Z = 0.612，P = 0.54）. Conclusion iRoot SP single⁃cone obturation and warm gutta⁃percha vertical condensationhad have similar therapeutic effect for diabetes complicated with periapical inflammation，but iRoot SP single⁃cone obturation was beneficial to reduce the occurrence of emergency reactions after root filling，and the periapical tissue healing after treatment may be faster than warm gutta⁃percha vertical condensation