Purpose: The purpose of this study was to identify the effects of a cognitive behavioral stress management program on perceived stress, coping strategies, and cortisol in people with Diabetes Mellitus Type 2. Method: Patients with type 2 diabetes were recruited from of a public health center in an urban area. Thirty-five participants (experimental group=17, and control group=18) enrolled. The experimental group received small group-based cognitive behavioral stress management training for eighty minutes per session, once a week for eight weeks. Data were collected at baseline and ninth week for perceived stress, affect-oriented coping, problem-oriented coping, and cortisol. The data were analyzed using SPSS 12.0. Results: The experimental group had significantly less perceived stress (t=-9.82, P<.001) and cortisol (t=-2.14, p=.040) than the control group. No significant group differences were found in affect-oriented coping (t=-.43, p=.673) or problem-oriented coping (t=1.40, P<.170). Conclusion: These results suggest that a cognitive behavioral stress management program can have positive effects on perceived stress and cortisol in patients with diabetes mellitus type 2. Further research with a larger sample and for a longer period is needed to expand our understanding of the effects of the program for patients with diabetes mellitus type 2.