OBJECTIVES : In patients with type 2 diabetes mellitus (T2DM), both treatment adherence and persistence help achieve glycemic control and improve health outcomes. However, given the known complexity of measuring adherence/persistence to injectables with prescription claims, current diabetes medication adherence/persistence quality measures do not include insulin. We conducted a retrospective cohort study to measure and compare treatment persistence and adherence among T2DM patients initiating basal insulin, wherein persistence and adherence were measured using previously published methods by Wei et al. and Slaubaugh et al., respectively. We also investigated the association of adherence/persistence with clinical and economic outcomes.

METHODS : Using the Truven Marketscan® dataset, we required patients to be ≥18 years of age with a diagnosis of T2DM, insulin naïve, and initiating basal insulin (index) during 2010 – 2014. We applied a continuous enrollment criteria for medical and drug coverage during 6-months pre- and 1-year post-index. We identified baseline factors associated with insulin adherence/persistence and estimated the impact on post-index clinical and economic outcomes.

RESULTS : A total of 16,149 patients with T2DM were included. Average insulin adherence/persistence post-index was 70.1% and 52.6%, respectively. Significantly higher insulin persistence and adherence was associated with older age, initiation on insulin pen, and having multiple medications. Male gender and having previous diabetes-related hospitalizations increased the likelihood of insulin adherence alone. Higher insulin treatment persistence and adherence were also associated with lower hemoglobin A1c at follow-up, lower healthcare utilization, and higher pharmacy costs. Only insulin persistence was associated with lower total healthcare costs and a greater reduction in A1C from baseline.

CONCLUSIONS : Treatment adherence/persistence among patients with T2DM initiating basal insulin are influenced by numerous factors. Greater insulin adherence/persistence is linked to improved clinical outcomes and reduced healthcare utilization. Such methodologies may be suitable for an insulin quality performance measure.