Comparative adherence to diabetes drugs: An analysis of electronic health records and claims data

Non-adherence to medications is a major challenge in diabetes care. The objective of this brief report is to compare adherence rates for 6 major classes of diabetes medications: metformin, sulfonylurea, thiazolidinedione, basal insulin, DPP-4 inhibitors, and GLP-1 receptor agonists. We used a data source that linked electronic prescriptions with insurance claims to assess whether new electronic prescriptions for diabetes medications were followed by dispensing claims consistent with that prescription. After one year of follow-up, the daily medication possession probability (MPP) - a measure of overall adherence - at one year for sulfonylurea was 0.49 and for metformin was 0.46. Thiazolidinediones and basal insulin had a similar final daily MPP at 0.36 and 0.39, respectively, which was significantly lower than that for sulfonylurea or metformin (P < .05). GLP-1 receptor agonists and DPP-4 inhibitors were also comparable to one another at a final daily MPP of .30 and .21, respectively (P < .05 compared to any of the aforementioned drug classes). In summary, the rates at which diabetes drugs are prescribed, and the rates at which patients actually take them, differ substantially. Physicians should be aware of potentially significant challenges concerning adherence to newer agents.