Abstract: Objective: This study was conducted to determine the effect of Stress Inoculation Training (SIT) on diabetes-related distress and stress in diabetic patients. Methods: Sixty-four diabetic patients were randomly assigned to either case or control group. The case and control groups received the same treatment and health education, the only difference was stress inoculation training administered in the case group, which was composed of eight 90min sessions over 8 weeks. Data were collected using Diabetes Distress Scale (DDS), The Problem Areas In Diabetes Scale (PAID) and the Chinese Version Perceived Stress Scale (CPSS) before and after the intervention. Results: The results showed that there was a significant difference between case and control groups in terms of diabetes-related distress and stress (P<0.01). Stress inoculation training reduced diabetes-related distress and stress in diabetes patients. Conclusion: SIT significantly reduced diabetes-related distress and stress. Therefore, teaching this skill and the strategies of coping with stress is recommended for these patients, in addition to medical treatment.