Behavioral Interactions Shaping the Use of a Mobile Health Intervention for Diabetic Foot Self-Care Among People With Diabetes and Caregivers: COM-B and TDF Qualitative Analysis

Background Mobile health (mHealth) interventions show promise for supporting diabetic foot self-care; however, sustained engagement remains a challenge, particularly in low- and middle-income countries. While educational strategies are commonly used to address diabetic foot ulcers, they often fail to translate knowledge into long-term self-care. Understanding behavioral mechanisms underlying mHealth use, including the role of caregivers, is critical for improving implementation and effectiveness. Objective This study explored how behavioral interactions between people with diabetes and caregivers shape the use of an mHealth app for diabetic foot self-care. Methods This qualitative explanatory study was embedded within a parent study of an mHealth app for diabetic foot care that was conducted in primary care settings in Peru. It used the COM-B (capability, opportunity, motivation–behavior) model and the Theoretical Domains Framework (TDF) to identify mechanisms relevant for intervention design and scale-up. Semistructured interviews were conducted with people with diabetes and caregivers about their experiences related to accessing the app. Data were analyzed using deductive and inductive thematic analysis informed by the COM-B and TDF. Results In total, 14 people with diabetes (median age 54 y, 8 women and 6 men) and 10 caregivers (median age 28.5 y, all women) were interviewed. The app use depended on varying interactions between COM-B domains, while other behavioral determinants aligned with a single domain. Across domains, interactions between people with diabetes and caregivers also affected the app use. For example, caregivers often compensated for physical capability limitations through foot positioning or environmental adjustments. Environmental context and resources, including internet access, lighting, and device compatibility, affected the app use for all participants. Motivation for all participants was largely driven by beliefs about the app’s preventive value, although reassurance from health professionals and altruism also emerged. Conclusions The app use often depended on collaboration between people with diabetes and caregivers as a dyad, rather than on independent users. This highlights the need to design digital interventions around caregiver demographics, competing responsibilities, and the additional responsibilities an app may introduce. Participants’ preference for individual follow-up suggests that nonphysician health personnel and other human support may help maintain continuity and reassurance alongside digital monitoring. Although the app was an early prototype intended for algorithmic training, participant experiences provided insight into real-world usability and contextual barriers for future app development.