Oral Antidiabetic Medication Adherence and Glycemic Control in Managed Care

Objective: To evaluate adherence to oral diabetes medications (ODMs) in patients with type 2 diabetes and the impact of ODM adherence on glycemic control.

Study Design: Retrospective observational study.

Methods: Medical and pharmacy claims from a managed care plan in Oregon were used to identify adults with diabetes who newly initiated ODM therapy (n = 2741); a subset of this cohort linked to electronic health records was used to evaluate the relationship between adherence and glycemic control (n = 249). Glycemic control was assessed based on most recent glycosylated hemoglobin (A1C) measurement within the study period.

Results: Mean cohort age was 54 years; 46% initiated therapy with metformin, 39% with a sulfonylurea, and 12% with a thiazolidinedione. Mean adherence overall was 81%, and 65% of subjects had good adherence (>80%). Increasing age and comorbidity burden were associated with higher medication adherence. In the patient subset with A1C measurements, mean baseline A1C was 8%. An inverse relationship existed between ODM adherence and A1C; controlling for baseline A1C and therapy regimen, each 10% increase in ODM adherence was associated with a 0.1% A1C decrease (P = .0004).

Conclusion: Although most patients were adherent to ODM therapy, adherent patients were more likely to achieve glycemic control than nonadherent patients. Greater efforts are needed to facilitate diabetes self-management behaviors to improve patient outcomes.