State Laws Significantly Impact Uptake of Interchangeable Biosimilar Insulin
A study using MarketScan commercial claims data revealed that state-level substitution laws have a significant influence on the adoption of biosimilar insulin glargine products in the US, underscoring the regulatory environment as a key barrier to biosimilar utilization.
Researchers looked at insurance claims data from August 2024 to January 2025, examining prescription fills for insulin glargine among individuals under 65 years old. They analyzed data from over 487 000 fills of the brand-name product Lantus (Sanofi) and its biosimilars, including the interchangeable Semglee and the noninterchangeable Basaglar.
Findings showed that states with less restrictive substitution policies saw a 7.03 percentage point increase in the market share of Semglee compared to more restrictive states (P = .008). Concurrently, the market share for branded insulin glargine (Lantus, Sanofi) dropped by 6.48 percentage points in these permissive states (P = .02). By the study’s final quarter, Semglee's market share reached 20.6% in less restrictive states, nearly double that in more restrictive ones (12.1%).
The study also identified specific regulatory requirements that suppressed biosimilar uptake, including enhanced physician notification (−8.15 pp), refill notifications (−4.68 pp), and patient notification requirements (−3.52 pp), with physician notification showing the strongest negative association (P < .001).
“…[R]eforms to substitution laws may be needed to clear undue barriers to substitution. One fruitful area of reform is revisiting the requirements regarding physician and patient notifications, given their ubiquity and pronounced associations with substitution,” said the authors.
These findings point to the crucial role state laws play in biosimilar adoption. The authors suggest that easing restrictive substitution laws could significantly improve biosimilar uptake, reducing drug spending while maintaining therapeutic efficacy. As biosimilars grow in prominence, especially in chronic disease management like diabetes, regulatory reform may be key to unlocking their potential benefits.
Reference
Kwon Y, Sarpatwari A, Dusetzina SB. State substitution laws and uptake of an interchangeable insulin biosimilar. JAMA Health Forum. 2025;6(4):e250406. doi:10.1001/jamahealthforum.2025.0406
