Background. Diabetes mellitus has several complications related to mental health, such as stress and depression. Stress may disrupt the self-concept of a person with type 2 diabetes mellitus (t2Dm). Objectives. the aim of this study was to analyze the relationship between stress and self-concept among t2Dm patients in medan, indonesia. Material and methods. this is a cross-sectional study of a total of 100 subjects. the subjects were selected using convenience sampling. the primary data were collected from interviews using questionnaire guidelines. the Perceived Stress Scale-10 was used to determine the stress level, while the tennesse Self-Concept Scale was used to determine the patient's self-concept. the data were processed using SPSS and analyzed with the chi-squared test. Results. the results showed that 83% of diabetic patients experienced a moderate level of stress, whereas 61% of patients had a fair self-concept. Furthermore, the chi-squared test showed that there was no relationship between stress and self-concept in t2Dm patients (p < 0.05). Conclusions. there was no relationship between stress level and self-concept among t2Dm patients (p < 0.05). although stress and self-concept are closely related, especially in t2Dm patients, the present study did not find a relationship between the two variables. however, efforts should still be made to prevent mental health disorders and to control the disease.