Objective To formulate a discharge readiness intervention program for type 2 diabetes mellitus (T2DM) patients based on Meleis′ Transition Theory and validate its efficacy. Methods The Meleis′ Transition Theory-based discharge readiness intervention program was developed through literature review, focus group discussions, and the Delphi expert consultation method. Using convenience sampling, 50 patients admitted to the endocrinology department from January to March 2024 were assigned to the control group (receiving routine discharge guidance), while 50 patients admitted from April to June 2024 were assigned to the intervention group (implementing the formulated program). Results At discharge, the intervention group exhibited significantly higher discharge readiness score than the control group (all P<0.05). At 3 months post-discharge, FPG, 2hPG, and HbA1c levels in the intervention group were significantly lower than both pre-intervention levels and those in the control group; the total self-management capacity score in the intervention group was significantly higher than that in the control group (P<0.05). Conclusion The Meleis′ Transition Theory-based discharge readiness intervention program effectively improves glycemic metabolic parameters, enhances discharge readiness, and self-management capacity in T2DM patients.