The present study aimed to compare the effectiveness of reality therapy and meaning therapy on internal self-talk and health-promoting lifestyle of patients with diabetes. The present study method was a quasi-experimental design with a multi-group pre-test-post-test design with a three-month follow-up with a control group. The statistical population included all people with diabetes referring to Taban Diabetes Center in Tehran. Using a purposive and accessible method, 45 samples were selected from among patients who had at least three years of type 2 diabetes and were randomly assigned to three groups of 15. The data collection tools were the self-talk questionnaire of Callot et al. (2005) and the health-promoting lifestyle questionnaire of Walker and Hill-Plerki (1996). After the pre-test, the first experimental group was subjected to Glaser reality therapy intervention in 8 group sessions based on the established protocol. The second experimental group, after the pre-test, underwent 8 group sessions of Frankl's semantic therapy intervention based on the established protocol. The control group did not undergo any intervention after the pre-test. All three groups were given a post-test after completing 8 sessions, and then, after three months of the intervention, the follow-up phase was conducted by re-administering the research questionnaires. Data analysis using repeated measures analysis of variance showed that reality therapy reduces negative self-talk in diabetic patients and increases positive self-talk in them. Meaning therapy increases positive self-talk in diabetic patients and reduces negative self-talk in them.