Do biosimilar insulins really match the originals?
The short answer is yes—when tested rigorously, biosimilar insulins are not inferior to their brand-name counterparts. In the INSTRIDE 1 and 2 trials, insulin glargine-yfgn (the first interchangeable biosimilar insulin) proved noninferiority in blood glucose reduction and adverse effect profile versus the reference insulin glargine [2]. Even in INSTRIDE 3, where patients were switched back and forth between the biosimilar and the originator throughout the trial, there were no statistically significant changes to glucose levels or adverse effects [2]. That means the biosimilar performs just as well in real-world use, including when patients are switched at the pharmacy counter without a new prescription.
Does switching patients to biosimilars cause problems?
A large real-world study in British Columbia, Canada, looked at what happened when a mandatory policy switched over 15,000 patients from originator insulin glargine to the biosimilar. Over the first year, they saw marginal increases in insulin use (2.5%), oral diabetes medication use (2.8%), and outpatient visits (1.4%)—but no signals of negative health impacts [1]. The increases were small and likely reflect extra monitoring or adjustments, not harm. This is reassuring: even when switching is forced, patients don't experience worse outcomes.
How do biosimilars improve access?
The main way biosimilars improve access is through cost. Insulin glargine-yfgn's list price is significantly lower than other insulin glargine products, and this market competition drives down prices of the originators too [2]. That means more patients who previously couldn't afford insulin can now get it. A 2024 proposal to add rapid-acting insulin analogues (including biosimilars) to the WHO Essential Medicines List argues that this would catalyze price reductions and improve global access, especially in low- and middle-income countries where affordability is a major barrier [4]. The same paper notes that three companies control 96% of the insulin market by volume, so biosimilars are key to breaking that stranglehold [4].
Are there any downsides or caveats?
While the evidence is strong, there are a few caveats. The British Columbia study was observational, not a randomized trial, so it can't prove cause and effect—but the large sample size and lack of harm signals are reassuring [1]. Also, biosimilars are not automatically interchangeable unless they earn that designation; insulin glargine-yfgn is the first to do so, but others may not be [2]. Finally, even with biosimilars, access issues remain in low-income countries due to storage, education, and stigma—not just cost [3]. So biosimilars are a big step, but not a complete solution.
About These Sources
This answer is built on 4 studies (3 peer-reviewed, 1 preprint) — published from 2021 to 2024, 2 from 2024 or later, 2 in Q1 journals — selected as the most relevant from 4 studies that passed quality screening, drawn from 62 papers retrieved from a database of over 500 million.
Sources used in this answer
The Impact of Mandatory Nonmedical Switching From Originator to Biosimilar Insulin Glargine
In a prospective cohort study of over 15,000 patients in British Columbia, a mandatory switch from originator to biosimilar insulin glargine led to marginal increases in insulin use (2.5%), oral antidiabetic use (2.8%), and outpatient visits (1.4%) but no signals of negative health impacts.
The First Interchangeable Biosimilar Insulin: Insulin Glargine-yfgn
Insulin glargine-yfgn, the first interchangeable biosimilar insulin, demonstrated noninferiority in blood glucose reduction and adverse effects versus reference insulin glargine in INSTRIDE 1 and 2 trials, and no significant changes in glucose or adverse effects during repeated switching in INSTRIDE 3.
Current and Future Strategies in Insulin Development and Treatment
A 2024 review highlights that while new ultra-rapid-acting and once-weekly basal insulins improve glycemic control and adherence, affordability and access remain major issues even in affluent countries, and biosimilars offer safe, cost-effective options, especially in low- and middle-income countries.
Proposal for the addition of Rapid-Acting Insulin Analogues (Insulin lispro, Insulin aspart, and Insulin glulisine) to the WHO Model List of Essential Medicines for the treatment of adults with type 1 and type 2 diabetes mellitus and for gestational diabetes and to the Essential Medicines List for Children for the treatment of type 1 and type 2 diabetes
A 2024 proposal to add rapid-acting insulin analogues (including biosimilars) to the WHO Essential Medicines List argues that this would improve access and reduce prices, noting that three companies control 96% of the insulin market by volume and that analogue production costs are only slightly higher than human insulin.