Gaps in Knowledge Persist Around Biosimilar Insulin Switching, Review Finds

Despite over a decade of biosimilar insulin availability and growing pressure on health care systems to adopt cost-saving alternatives, a new scoping review revealed that stakeholders across the care continuum remain uncertain about switching.1

Published in Endocrinology, Diabetes & Metabolism, the review aimed to systematically map and summarize existing literature on the perceptions and experiences of biosimilar insulin switches among health care professionals (HCPs), health service administrators (HSAs), and people with diabetes. The authors were motivated by the increasing prevalence of managed switch programs and the apparent lack of evidence guiding their implementation. In the UK alone, freedom of information requests had identified at least 13 regions that had already undertaken some form of biosimilar insulin switch program, with 6 more planning to do so.

Researchers searched 3 bibliographic databases (PubMed, Web of Science, and CINAHL Ultimate) and conducted supplementary gray literature searches of regulatory agency and patient advocacy group websites. Of 235 total records identified, 20 met inclusion criteria. Eligible articles included research studies (n = 8), reviews (n = 8), guidance documents (n = 3), and 1 opinion piece, published from January 2014 onward across countries, including the US, UK, Canada, Japan, Belgium, and India. No restrictions were placed on patient characteristics or health care setting.

HCP Perspectives

Awareness of biosimilar principles was high among HCPs across the included studies, with pharmacists demonstrating the strongest knowledge base. However, 67% of surveyed HCPs reported a lack of practical switching experience. Concerns about safety and efficacy were elevated when switching established patients compared with initiating biosimilars in insulin-naive patients, and diabetologists expressed notably higher concern than specialists in other fields; fewer than 10% of gastroenterologists reported major concerns, compared with rates reaching 63% among nurses and up to 50% among pharmacists when asked about switching efficacy.

Barriers to prescribing included a perceived lack of long-term safety data, uncertainty about interchangeability, and concerns over differences in delivery devices. Several HCPs and guidance documents recommended against switching patients whose glycemic control was already satisfactory. Pharmacy-level substitution—switching without prescriber input—was considered a contested practice by many HCPs, who also raised concerns about the workload implications of managing device transitions. Notably, no studies documented the actual experiences of HCPs who had participated in a biosimilar insulin switch.

Patient Perspectives

Only 3 research studies examined perspectives or experiences of people with diabetes, drawing from populations in the US, Canada, and Japan. A 2014 US study found that the majority of respondents (66%) expressed positive views about theoretically switching to a biosimilar insulin, with only 5% of people with type 1 diabetes indicating they would definitely not use one. Reasons for hesitancy included satisfaction with current therapy, perceived brand quality of the reference product, and prior negative experiences with generic drug switching.

A Japanese study found no meaningful change in treatment satisfaction, efficacy, or adverse events among patients with type 2 diabetes who switched from reference to biosimilar insulin glargine. A Canadian study examining a mandatory switch policy found that only 2.8% of patients subsequently returned to the reference product, though the authors noted that a strong financial incentive to remain on the biosimilar may have influenced that outcome. No studies examined patient perspectives specifically within publicly funded health care systems where cost is not a direct patient concern.

HSA Findings and Financial Themes

HSAs were primarily focused on administrative considerations, including formulary selection, legal responsibilities, and the need for structured transition plans. One Canadian study found no increase in healthcare resource utilization following a mandatory switch program. Financial themes ran throughout the literature: in publicly funded systems such as the UK's National Health Service, HCPs cited cost as the dominant prescribing consideration but noted that only modest price differences between products could serve as a disincentive.

The authors acknowledged several limitations. The body of literature was small, and most studies originated in higher-income countries, limiting applicability to low- and middle-income settings. Some earlier studies, published between 2014 and 2018, may not reflect current stakeholder attitudes, as biosimilar adoption has matured. Because this was a scoping review, no formal critical appraisal of included studies was conducted, restricting the authors' ability to assess evidence reliability.

The review concluded that high-quality, context-specific research is needed to meaningfully guide healthcare systems in implementing biosimilar insulin switch programs in ways that are acceptable to both clinicians and the people they treat.

References

1. Hindley B, Wright S, Ooi C, Da Costa R, Cope L. Exploring stakeholder perceptions and experience of biosimilar insulin switching: a scoping review. Endocrinol Diabetes Metab. 2026;9:e70142. doi:10.1002/edm2.70142