Barriers to adoption of biosimilar insulins in Europe: A mixed-methods study

Background: Despite the introduction of biosimilar insulins to improve affordability and enhance patient access, their adoption remains limited in Europe. Objectives: This study aims to (i) provide an up-to-date overview of EMA-approved insulin products and their reimbursement status across selected European countries, and (ii) explore the key factors influencing physicians' prescribing decisions regarding biosimilar and originator insulin. Methods: A mixed-method design was applied, comprising (i) a quantitative analysis of EMA-approved insulin products and their reimbursement status in nine European countries, and (ii) semi-structured interviews with physicians (N = 20). Results: Between 1996 and 2022, 43 insulin products received EMA approval, including six biosimilars (14.0%). Over 95% of approvals originated from three manufacturers: Novo Nordisk (39.1%), Sanofi (32.6%) and Eli Lilly (23.9%). Across the nine European countries, an average of 56.3% of EMA-approved insulin products, including biosimilar insulins, were reimbursed, ranging from 71.7% in the Netherlands to 41.3% in Belgium. The proportion of originator and second-generation insulin analogs was consistently higher than that of biosimilar insulins. In the qualitative phase, six thematic domains influencing physician prescribing choices for insulin products were identified, encompassing a total of 14 distinct factors. Prominent domains included (i) product-related (second-generation insulin analogs, and drug-device compatibility), (ii) pharmaceutical industry-related (company reputation trustworthiness, and marketing activities) and (iii) physician-related factors (habit persistence). Conclusion: This study highlights interrelated factors contributing to the limited adoption of biosimilar insulin in Europe. Addressing these barriers through targeted policy interventions may support more informed decision making and facilitate biosimilar insulin adoption in the future.