Objective To explore the experiences of barriers to sustaining self-management behaviors in young and middle-aged adults with type 2 diabetes, and to provide a reference for developing long-term self-management programs. Methods Interpretative phenomenological analysis was used.A purposive sample of 17 young and middle-aged adults with type 2 diabetes were recruited for in-depth semi-structured interviews.After completing within-case and cross-case thematic construction, the Temporal Self-Regulation Theory was introduced as an explanatory framework during the interpretative refinement stage to deepen the understanding of the experiential themes. Results The experiences of barriers to sustaining long-term self-management were interpreted into three themes and eight sub-themes:health goals failing to sustain action (insufficient awareness and neglect of future risks, immediate gratification undermining health-promoting behaviors); the relinquishment of behavioral agency (learned helplessness, the dual effects of social support, peer modeling induced behavioral alienation); cognitive contextual mismatch as a constraint on self-regulation (cognitive ambiguity leading to behavioral deviations, time conflicts and interruptions in execution,role conflicts and priority misplacement). Conclusion Young and middle-aged adults with type 2 diabetes report various barriers to maintaining long-term self-management behaviors.Medical staff should dynamically assess patients′ self-management ability and develop personalized management program based on patient characteristics to enhance their long-term self-management efficacy.