A systematic review of adherence with medications for diabetes

OBJECTIVE - The purpose of this study was to determine the extent to which patients omit doses of medications prescribed for diabetes. RESEARCH DESIGN AND METHODS - A literature search (1966-2003) was performed to identify reports with quantitative data on adherence with oral hypoglycemic agents (OHAs) and insulin and correlations between adherence rates and glycemic control. Adequate documentation of adherence was found in 15 retrospective studies of OHA prescription refill rates, 5 prospective electronic monitoring OHA studies, and 3 retrospective insulin studies. RESULTS - Retrospective analyses showed that adherence to OHA therapy ranged from 36 to 93% in patients remaining on treatment for 6-24 months. Prospective electronic monitoring studies documented that patients took 67-85% of OHA doses as prescribed. Electronic monitoring identified poor compliers for interventions that improved adherence (61-79%; P < 0.05). Young patients filled prescriptions for one-third of prescribed insulin doses. Insulin adherence among patients with type 2 diabetes was 62-64%. CONCLUSIONS - This review confirms that many patients for whom diabetes medication was prescribed were poor compliers with treatment, including both OHAs and insulin. However, electronic monitoring systems were useful in improving adherence for individual patients. Similar electronic monitoring systems for insulin administration could help healthcare providers determine patients needing additional support.