Can a modified theory of planned behavior explain the effects of empowerment education for people with type 2 diabetes?

Background: The effectiveness of the Patient Empowerment Program (PEP) has been demonstrated in people with diabetes mellitus (DM); however, the underlying reasons for its effectiveness remain unclear. To improve effectiveness, we need to study the psychological mechanism(s) of PEP to understand why it is effective. This study hypothesized that the Theory of Planned Behavior (TPB), modified specifically for people with DM, could describe the mechanism explaining PEP effects. Methods: A longitudinal design was used. Patients with type 2 DM (n = 365; 151 males; mean age = 62.9 ± 9.6 years) received two education sessions (i.e. seminars delivered by registered nurses to provide disease-specific knowledge), and some (n = 210) further enrolled afterwards in five empowerment sessions (i.e. small-group interactive workshops conducted by social workers to practice action planning, problem solving, and experience sharing). Validated questionnaires were used to measure risk perception, health literacy, attitude, subjective norm, perceived behavioral control and behavioral intention on diabetes self-care behaviors, and four diabetes self-care behaviors (diet control, exercise, blood glucose monitoring, and foot care) at baseline. Three months later (i.e. at the end of PEP), all participants completed the behavioral intention and diabetes self-care behaviors measures again. Attitude, subjective norm, perceived behavioral control, behavioral intention, and diabetes self-care behaviors were assessed to represent the TPB constructs. Risk perception and health literacy elements relevant to people with DM were assessed and added to modify the TPB. Results: The behavioral intention was associated with three diabetes self-care behaviors: exercise, blood glucose monitoring, and foot care. The behavioral intention was found to be a significant mediator in the following relationships: empowerment session participation and exercise (β = 0.045, p = 0.04), and empowerment session participation and foot care (β = 0.099, p