Medication Adherence and Associated Hemoglobin A1c in Type 2 Diabetes

Abstract

BACKGROUND: Tight blood glucose control has been correlated with a reduction in diabetes complications. Adherence to antidiabetic medications is crucial to achieving blood glucose control. OBJECTIVE: To assess the relationship between good glucose control [glycosylated hemoglobin (HbA 1c) levels] and adherence to prescribed treatment in patients on a stable medication regimen for type 2 diabetes. METHODS: The Morisky survey, a 4–item questionnaire that predicts patient medication-taking behavior, was used to assess adherence in 301 patients. The relationship of HbA 1c to Morisky score was evaluated, controlling for other variables related to patient demographics and clinical characteristics. Data were analyzed using a general linear model on log (HbA 1c). RESULTS: Unadjusted mean HbA 1c values (capped at 14.0%) for patients with Morisky scores of 0 or 1, 2, 3, and 4 were 8.92%, 8.67%, 7.74%, and 7.60%, respectively. Of all patients, 13.0%, 14.0%, 24.3%, and 48.8% had scores of 0 or 1, 2, 3, and 4, respectively. Good adherence (Morisky score ≥3) was associated with a 10% lower total HbA 1c (p = 0.0003) adjusted for all other factors in the model. Duration of diabetes (5–10 y) and presence of diabetes complications were also significantly associated with HbA 1c (p = 0.026 and 0.002, respectively). Adherence was poor in 27% of patients. CONCLUSIONS: This study found that patients with a higher score on the Morisky scale had a lower associated HbA 1c measurement. The Morisky score may be an efficient tool for identifying patients with poor medication-taking behavior who can then be targeted for directed adherence counseling services.