Designing an Equity-Oriented Dietary Self-Management System for Long-Term Care Residents with Type 2 Diabetes: Participatory Co-Design and Usability Testing

Older adults with type 2 diabetes (T2D) in long-term care face dietary self-management challenges arising from standardized routines, sensory and cognitive variability, and reliance on caregivers. This study used participatory co-design to develop and preliminarily evaluate an equity-oriented digital dietary management prototype. From June 2024 to December 2025, a four-phase study was conducted at a long-term care facility in Beijing, China. Semi-structured interviews with 20 stakeholders (12 residents, 5 family caregivers, and 3 nurses) and a one-day shadowing observation of one of these residents informed a 90 min co-creation workshop with 20 stakeholders (12 residents, 4 family caregivers, and 4 nurses) and iterative prototyping. All 12 residents in the workshop had participated in the interviews, including the resident involved in the shadowing observation. The resulting high-fidelity prototype integrated a consolidated reminder dashboard, an adaptive portion-control slider, and glucose–meal feedback visualization. Task-based usability testing with an independent sample of 12 participants (6 residents, 3 family caregivers, and 3 nurses) who had not participated in the preceding phases yielded a mean task-success rate of 94.44% (SD 0.43), a mean task-completion time of 1.9 min (SD 0.40), a mean error count of 0.33 per session (SD 0.47), a mean System Usability Scale score of 81.0 (SD 5.23), and satisfaction of 4.5/5 (SD 0.50). Qualitative feedback indicated that participants perceived the prototype as easy to navigate and potentially supportive of resident autonomy and coordinated record-keeping. These findings provide preliminary support for its usability and acceptability in the evaluated tasks. Field studies are needed to assess implementation, workflow effects, and behavioral or clinical outcomes.