Barriers to Medication Adherence in Poorly Controlled Diabetes Mellitus

Purpose: The purpose of this study is to characterize the adherence and medication management barriers for adults with poorly controlled type 2 diabetes mellitus (DM) (those with A1c 9% or above) and to identify specific adherence characteristics associated with poor diabetes control.

Methods: This was a cross-sectional analysis of baseline data from a randomized, controlled diabetes intervention conducted in University of Washington (UW) Medicine Clinics in the greater Seattle, Washington, area. The goal of the original study was to evaluate the effect of a pharmacist intervention on improving diabetes control over 12 months. Evaluation measures for medication adherence included self-reported adherence and medication management challenges using the Morisky question format and difficulty with taking medications for each diabetes medication based on the Brief Medication Questionnaire. Specific adherence characteristics associated with poor diabetes control (A1c >9%) were identified using multivariate regression analysis.

Results: Seventy-seven subjects (mean A1c, 10.4%; mean duration of DM, 7 years) were studied. The most common adherence challenges included paying for medications (34%), remembering doses (31%), reading prescription labels (21%), and obtaining refills (21%). Taking more than 2 doses of DM medication daily (beta = .78, SE = 0.32, P = .02) and difficulty reading the DM medication prescription label (beta = .76, SE = 0.37, P = .04) were significantly associated with higher hemoglobin A1c. Self-reported adherence was not related to A1c control.

Conclusions: In this study, we identified 2 factors that were associated with poorer A1c control. These findings highlight the importance of identifying potential challenges to medication adherence for those with DM and providing support to minimize or resolve these barriers to control.