Best fit framework synthesis of qualitative studies on factors associated with medication nonadherence in people with type 2 diabetes using the COM‐B model

This review aimed to synthesize factors associated with medication nonadherence among people with type 2 diabetes (PwT2D), using the Capability, Opportunity, Motivation and Behaviour (COM‐B) model as the a priori model. Studies published between January 2014 and April 2024 were searched on five databases. Studies were included if they recruited PwT2D aged >18 years, investigated factors associated with adherence to oral and/or nonoral medications for diabetes, used qualitative research methods, were conducted in a community setting, were in English language and had accessible full‐text articles. Best fit framework synthesis was undertaken, which led to the development of a hypothesized COM‐B variant model specific to medication nonadherence among PwT2D. Study quality was assessed using published criteria to evaluate whether the study was adequately reported. Twenty‐two studies were included. Factors were mapped onto the COM‐B model: physical capability (e.g., difficulty injecting insulin independently), psychological capability (e.g., understanding about diabetes), physical opportunity (e.g., cost of medication), social opportunity (e.g., quality of communication and relationship with healthcare providers), automatic motivation (e.g., habit formation) and reflective motivation (e.g., perceived necessity and effectiveness of medications). Reflective motivation had the most themes, while physical capability only had one theme. Personality was a theme that could not be mapped onto the model. Interactions between some COM‐B components (e.g., capability and motivation) were observed. This theoretically grounded synthesis may facilitate future intervention development by formulating a programme theory and identifying behaviour change techniques to address the identified factors.