Introduction: Concerns over cost-related non-adherence and high patient out-of-pocket (OOP) costs for insulin has prompted policies limiting insulin copays. This study examines the associations of insulin OOP cost by policy-relevant groupings, with gaps in therapy and insulin dose, expanding on current cost-related non-adherence data.

Methods: This retrospective cohort study included patients from the OptumLabs® Data Warehouse, a longitudinal, real-world data asset with de-identified administrative claims and electronic health record data, with commercial insurance, type 1 (T1D) or 2 diabetes (T2D), and insulin claims between 2006 and 2018. Index date was January 1 following two insulin claims at least 30 days apart in the prior year. Patients were grouped by average insulin OOP cost per 30-day supply over 1-year of follow-up: $0, >$0-$20, >$20-$35, >$35-$50, and >$50. Descriptive statistics were used to assess the proportion of patients with a >/=90 continuous-day gap in insulin therapy and insulin daily average consumption (DACON) by OOP group.

Results: A total of 21,085 and 72,512 patients with T1D and T2D, respectively, were included. Mean age was 40.6 and 53.9 years. More patients with T2D in OOP groups $35-$50 (29.7%) and >$50 (34.2%) experienced a 90-day gap in therapy vs. >$0-$20 (28.3%, p ≤0.02 for both). These groups also had a significantly lower mean (SD) DACON at 67.2 (136.1) and 63.9 (159.3) units/day vs. >$0-$20 at 72.8 (133.7) units/day, p <0.001 for both. In the T1D OOP groups, DACON did not differ by OOP group, and only the >$50 OOP group had significantly more patients with a gap in therapy vs. >$0-$20 (22.7% vs. 19.6%, p =0.003).

Conclusions: In commercial patients, insulin OOP costs >$35 were associated with gaps in therapy, and a decrease in average daily insulin dose in those with T2D. However, those with T1D may exhibit an inelastic demand to insulin in this patient population, as it is life-saving medication.


N. Ruiz-negron: Research Support; Self; Genentech, Inc., Novartis Pharmaceuticals Corporation. J. Sullivan: None. J. Tucker: None. C. Mcadam-marx: None.


Robert Wood Johnson Foundation; Health Data for Action Research Program (ID77105)

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