Self-care is a set of actions that individuals take to maintain life, good health, and well-being. Regardless of the type of diabetes, individuals must perform self-care and comply with the treatment to prevent complications, achieve better disease management, and maintain their quality of life. This study aimed to examine self-care behaviors of liver, kidney, and bone marrow transplant patients with diabetes. The study has used a descriptive correlational design and was carried out in an endocrinology and diabetes center in Brazil. A total of 101 patients participated in the study. The Diabetes Self-care Activities Questionnaire was used, and the quantitative analysis was carried out using SPSS. The results show that the highest self-care levels occurred in the medication domain, while the lowest were found in the specific diet domain. Some important correlations were found: men were more likely to assess blood glucose, use combined oral/insulin therapy, take insulin, and take medications as prescribed than women; patients on combined oral/insulin therapy followed dietary recommendations more frequently than the others; and patients with altered serum urea and history of stroke had high levels of self-care. The results made it possible to know the compliance in performing self-care activities in transplanted patients with diabetes, supporting the development of interventions to motivate and improve self-care.