The objective of this study was to assess the effect of Buddhist group therapy on patients with type 2 diabetes who had depressive symptoms. A quasi-experimental design study using a control group with matching technique was conducted. After informed consent was obtained, the “Nine questions for assessing depressive disorder symptom” (Isan language) was used to determine the patient's condition. A total of 62 patients with type 2 diabetes who had depressive symptoms were assigned to either the experimental group (n = 32) or the control group (n = 32). Patients in the experimental group were divided further into four groups (8 patients per group) and attended the Buddhist group therapy. The intervention consisted of a weekly Buddhist group gathering lasting 2 hours for 6 weeks plus home meditation practices. Patients in the control group received treatment as usual. Both groups received standard physician treatment, including medication. Physicians did not know who was in either the control or experimental groups. Results show that 6 months after the intervention, 65.6% and 100% of patients in the control group and experimental group, respectively, returned to normal level. The intention-to-treat analysis, which included two participants in the experimental group lost follow-up, yielded a small reduction in the number of patients who returned to normal level (93.8%). With intention-to-treat analysis, the relative risk on depressive symptoms between the experimental and control groups was 6.5 (95% confidence interval, 1.4–30.6). Qualitative data from the experimental group supported that there were therapeutic group factors involved. However, patients realized the truth of being oneself and also accepted their current living condition. In conclusion, this program is effective in reducing depressive symptoms.