A new study published in the Journal of General Internal Medicine and led by Jonathan H. Watanabe, PharmD, MS, PhD, chair of the UCSF School of Pharmacy’s Department of Clinical Pharmacy, shows how switching to lower-cost biosimilar versions of once-daily insulin expanded access to diabetes care and generated an estimated $19 million in savings across the University of California health system in 2022 alone.

“Historically, insulin has been one of the most expensive drugs in the world. So many people require it, yet it’s often been unaffordable,” Watanabe said. “There’s been an effort for decades to develop what are essentially generic versions of these biologic meds, but until now, there hadn’t been a comprehensive study over time of how that impacted use, spending, and savings. That’s what we set out to understand.”

Using the UC Health Data Warehouse to draw on a decade of patient data, the study found that after biosimilar insulin glargine products became available — Basaglar in 2016 and Semglee in 2020 — amount spent per patient using insulin dropped across all patient age groups.

“That's really what we wanted to see, that the availability of this less expensive version not only reduces costs for those that use it, but allows us to treat more patients overall because it's less expensive,” Watanabe said. “This really affects everybody when it comes to affordability of biologic medicines that are now commonly used.”

From cost savings to health policy

For Watanabe, the findings have important public health implications, given how long insulin was the No. 1 drug by total Medicare spending, and given insulin’s prominence in statewide and national discussions about regulating prescription drug prices.

The study, which leveraged data from more than 110,000 insulin users across the UC system’s five medical centers, demonstrates how academic health systems can drive change by using integrated data to inform policy and improve access.

“This research is really a demonstration of what only the University of California can do,” Watanabe said, “in terms of a health system that funds this data asset and allows it to be available to researchers to tackle timely current issues like this.”

Looking ahead with biosimilar adoption

The findings also point to what’s next: Ensuring that biosimilars are developed and adopted more quickly, so their benefits reach patients sooner. Lower out-of-pocket costs for patients could support better adherence and satisfaction, underscoring the link between affordability and health outcomes.

Beyond its economic impact, the study also revealed changes in prescribing patterns as confidence in biosimilar safety and efficacy grew.  

“That’s where pharmacists can play an essential role, by educating patients, providers, and payers on the evidence supporting biosimilars and ensuring they’re used appropriately,” Watanabe said, adding that pharmacists are often the first to identify cost barriers and guide patients toward effective, lower-cost alternatives.

“We need to place more emphasis on how to increase both the uptake and the development of biosimilars — getting them to market faster and creating policy incentives that expand their availability,” Watanabe said. “Insulin is almost on the way out now as the primary focus for many drug firms, with many companies shifting their priorities to newer agents like the GLP-1s — Ozempic, Wegovy, and others — that can reduce or replace insulin use. But the lessons here still apply as biosimilars for those medications are on the horizon.”

Applying similar research approaches to track real-world use of emerging diabetes medications, Watanabe said, could help policymakers and health systems balance innovation and access as the therapeutic landscape continues to evolve.