Background: One of the effective factors in preventing the complications of diabetes is stress management. The purpose of this study is to evaluate the effect of intervention based on Lazarus' Transactional model on the level of stress in patients with type 2 diabetes. Materials and Methods: this quasi-experiment study was done among 80 patients with type 2 diabetes. Stress level, coping methods and hemoglobin A1C were evaluated before and three month after the intervention. In the intervention group, based on the strategies predicted in the model, five training sessions were held. The data were analyzed by using paired t-test, student's t-test, Analysis of Variance and Pearson's correlation coefficient. Results: In the studied population, there was no significant relationship between stress level and demographic characteristics. Independent t-test showed that the stress score after the intervention was significantly lower in the intervention group (P<0.001. (there was no significant difference in the HbA1c in the groups after intervention ( P=0.66( , However, in the intervention group, the amount of hemoglobin A1c showed a significant decrease compared to before the intervention. The use of effective coping strategies increased in the intervention group (p<0.05). Conclusion: The present study showed that training and intervention to use coping approaches using Lazarus' Transactional model of stress and adaptation can be effective in controlling and reducing stress in patients with type 2 diabetes.