Assessing barriers to diabetes medication adherence using the Information-Motivation-Behavioral skills model

Medication nonadherence is a prevalent and costly problem among patients with type 2 diabetes. Applications of theory can inform and improve adherence promotion interventions. We used a new assessment based on the Information-Motivation-Behavioral skills (IMB) model of adherence to assess patient-reported barriers and test the theoretical model.

Participants (N = 237) completed a card sorting task to identify barriers to adherence, a survey, and a hemoglobin A1c (HbA1c) test. We identified the most commonly reported adherence barriers and examined associations between patient characteristics and barriers mapped onto each of the IMB constructs. We used structural equation modeling to test the IMB model and determine if barriers as reported on this measure predict patients' self-reported diabetes medication adherence and, in turn, HbA1c levels.

The most frequently reported barriers were forgetting doses, thinking brand name medicine works better than generic medicine, not seeing immediate benefit, and feeling burned out with taking diabetes medicine. Younger age and lower health literacy were associated with higher barrier scores for all IMB model constructs. Information and social motivation barriers affected adherence via behavioral skills barriers (indirect effects -0.19, CI [-0.33, -0.09] and -0.24, CI [-0.37, -0.14], respectively). The IMB barrier constructs explained 44% of the variance in diabetes medication adherence which, in turn, was significantly associated with and explained 8% of the variance in HbA1c (both p < .001).

Results suggest this assessment task can identify patient-specific barriers to diabetes medication adherence. Interventions targeting patient-specific barriers using this assessment could improve adherence and HbA1c.