The Impact of Insulin Out-of-Pocket Caps among Commercially Insured Diabetes Patients

In January 2021, 8 states capped insulin out-of-pocket (OOP) costs at $25-$100 per 30-day supply. We examined the impact of these state policies on insulin OOP costs and use among commercially insured members with diabetes. Given that members in high-deductible health plans with health savings accounts (HSA) pay the full price of insulin before reaching their annual deductible, we hypothesized that these members would be the most impacted by the policies. We took advantage of a natural experiment created by state variation in policy to employ a robust quasi-experimental design. We used a pre-post with control group study design, with unadjusted difference-in-differences analysis, to evaluate changes in outcomes from 2020 (pre-policy) to 2021 (post-policy) in the 8 intervention states compared to contemporaneous changes in outcomes in 40 control states. We measured (1) insulin OOP cost per insulin user per year and (2) 30-day insulin fills per diabetes patient per year, and stratified results by HSA vs. non-HSA plans. We included 450,351 commercially insured members diagnosed with diabetes enrolled in a large, national health plan (19% were in an HSA plan). For the OOP cost analyses, we included 70,904 members with non-zero insulin costs. Among members with diabetes in HSA plans, state insulin OOP caps were associated with a $178 (95% CI: -$239, -$116) absolute and 18% (95% CI: -24%, -12%) relative reduction in annual OOP insulin costs. However, insulin fills among members with diabetes in HSA plans were unchanged (0.01 fills [95%: -0.05, 0.08]). The state policies also had no impact on annual OOP insulin costs or insulin fills for members with diabetes in non-HSA plans. State policies that capped insulin OOP costs were effective in reducing financial burden among HSA members but did not increase insulin use. Furthermore, the policies had little impact among members in plan types with lower baseline cost-sharing. These findings shed light on the potential impact of Medicare’s insulin copayment cap policy. Disclosure L.F.Garabedian: None. D.Ross-degnan: None. R.Costa: None. S.Argetsinger: None. F.Zhang: Other Relationship; GlaxoSmithKline plc., Pfizer Inc. J.Wharam: None. Funding Centers for Disease Control and Prevention (U18DP006527)