M-health apps have been considered as a promising tool to support disease management anytime and anywhere at a low cost. However, very few studies have provided an understanding of patients’ acceptance and continuous use through a longitudinal approach. The study proposed and validated a two-stage model to explain patient acceptance and continued use of a self-management system. A total of 160 type 2 diabetic patients were recruited. They received an M-health app to perform disease management during a 12-week period. Patients’ perception regarding the use of the system were measured at baseline and/or 12-week follow-up. A partial least squares structural equation modeling approach was used for model estimation. Perceived usefulness (PU) is significantly related to the behavior intention (BI) to use the system at the initial use stage; however, the relationship becomes weaker after 12 weeks. Perceived ease of use (PEOU) was found to have indirect influence on BI through PU at initial stage. PU and PEOU at later use stage were significantly affected by their perceptions at initial use stage. Moreover, BI at the initial stage was not found to significantly influence actual use during the 12-week period. Actual use was found to significantly influence satisfaction and PEOU, but not PU, at later use stage. Satisfaction significantly influenced patient continuance intention after 12 weeks. This finding highlights the importance of further examine acceptance behavior through longitudinal perspective. The findings provide important implications for the design and implementation of self-management systems for patients with chronic diseases.