Diabetes mellitus (DM) is the condition of metabolism affected by chronic hyperglycemia (the increase of glucose levels in the blood) caused by insulin secretion defect. One of the non-pharmacological therapies used to decrease the type 2 DM is cognitive behavioral therapy. The objective of the research was to identify the effect of Cognitive Behavior Therapy (CBT) on self management and self-care behaviors of type 2 DM patients. The research used a quasi-experimental method with a two-group pretest-posttest design. The samples were 70 respondents with 35 of them were in the intervention group and the other 35 were in the control group, taken by using a consecutive sampling technique. The data were gathered using the Diabetes Self-Management Questionnaires (DSMQ) and the Summary of Diabetes Self-Care Activities (SDSCA) questionnaires. The gathered data were analyzed by using paired t-test, and independent t-test. The results of the study showed that there were significantly differences of mean scores of self management and self care behaviors between intervention and control groups (t=13.24; p=0.00) and(t=14.63,p=0.00), respectively. It is recommended that cognitive behavior therapy can be used as one of the non-pharmacological therapiesto change self-care behaviors in type 2 DM patients.