Adherence to Basal Insulin Therapy Among People with Type 2 Diabetes: A Retrospective Cohort Study of Costs and Patient Outcomes

INTRODUCTION: This research compares costs, resource utilization, and complications between adherent and nonadherent patients over the 3-year period post initiation on basal insulin therapy. METHODS: Research Databases from 2011 through 2015. Adults aged 18 years or older and identified with type 2 diabetes (T2D) who initiated therapy on basal insulin in 2012 were included. Patients were excluded if they were pregnant, filled their index basal insulin prescription via mail order, or were not continuously insured from 1 year before through 3 years following initiation of treatment with basal insulin. Instrumental variables were used to control for selection bias, and multivariable analyses were used to examine the associations between adherence to basal insulin therapy and costs, resource utilization, and acute complications. RESULTS: A total of 21,363 individuals were included in the study. Three years after initiating therapy on basal insulin, patients who were adherent over time to basal insulin treatment therapy (33.8% of patients) had significantly higher diabetes-related drug costs. However, patients' adherence was associated with significantly lower diabetes-related outpatient, acute care, and total costs. Results for all-cause costs were similar. Adherent patients also had significantly fewer all-cause and diabetes-related hospitalizations and emergency room visits and were significantly less likely to be diagnosed with an acute complication. CONCLUSIONS: Results of this study illustrate that despite higher drug costs, there are disease-specific and all-cause cost offsets and improved patient outcomes associated with adherence to basal insulin therapy for people with T2D. FUNDING: Eli Lilly and Company.