Insulin

Insulin is the peptide hormone that started biotechnology as an industry — the first drug of any kind made with recombinant DNA (1982), replacing a century of animal-extracted supply. It's also the peptide drug most people already know by reputation for a different reason: a decades-long US pricing crisis that only started meaningfully closing in the last three years, through a mix of a federal cap, a biosimilar market, and — as of late 2025 — direct manufacturer pricing deals.

From cadaver-extracted to genetically engineered

Insulin was first isolated and used therapeutically in 1921-1922 at the University of Toronto (Frederick Banting, Charles Best, James Collip, and J.J.R. Macleod), and for six decades afterward, every commercial insulin was extracted from pig and cattle pancreases — an animal-dependent supply chain with real batch-to-batch variability. That changed on 29 October 1982, when the FDA approved Humulin (Eli Lilly, using Genentech's recombinant technology) — the first genetically-engineered pharmaceutical product ever approved, of any kind, for any condition. Human-sequence insulin produced in bacteria replaced the need for an animal source entirely, and every insulin analog developed since (lispro, aspart, glargine, degludec, and others) builds on that same recombinant-production approach.

The century-long pricing story, and its recent turn

US insulin list prices rose sharply from the 1990s through the 2010s even as the drug itself changed little, producing a well-documented affordability crisis — patients rationing doses, and a number of reported deaths tied directly to insulin rationing. Two changes in the 2020s materially altered that picture:

• The Inflation Reduction Act's Medicare cap. Effective 1 January 2023, out-of-pocket costs for a month's insulin supply are capped at $35 for Medicare Part D enrollees — a federal statutory cap, not a voluntary manufacturer program.
• 2025-2026 "most-favored-nation" manufacturer agreements. Following the 12 May 2025 executive order "Delivering Most-Favored-Nation Prescription Drug Pricing to American Patients," the administration announced agreements through late 2025 with major manufacturers — including Novo Nordisk (covering NovoLog and Tresiba) and Sanofi — to price insulin at $35 per month (insulin lispro as low as $25) through TrumpRx, a federal direct-purchase pricing platform that officially launched 5 February 2026, extending $35-range insulin pricing beyond Medicare enrollees specifically.

Biosimilar insulin: a real substitution option now

On 28 July 2021, the FDA approved Semglee (insulin glargine-yfgn, Mylan/Viatris and Biocon) as the first interchangeable biosimilar insulin product — a specific FDA designation (distinct from an ordinary biosimilar approval) that lets a pharmacist substitute it for the reference product, Sanofi's Lantus, without requiring a new prescription, the same way a generic small-molecule drug can be substituted. This mattered for a genuinely structural reason: unlike small-molecule drugs, biologic products like insulin are manufactured in living cells and can't be copied atom-for-atom, so a biosimilar approval pathway (and the stricter "interchangeable" designation specifically) took decades longer to reach insulin than ordinary drug generics did for other medicines.

Where it differs from the GLP-1 drugs on this site

Insulin and the GLP-1/GIP-agonist drugs covered elsewhere on this site (semaglutide, tirzepatide, and others) are frequently confused by newcomers because both are injectable peptide hormones used in diabetes care, but they do different jobs: insulin directly lowers blood glucose by enabling cells to take it up, and is essential, not optional, for anyone whose own insulin production has failed (all type 1 diabetes, and type 2 diabetes once other treatments no longer control glucose). GLP-1/GIP drugs instead work upstream — slowing digestion and increasing the body's own insulin response — and were developed later, primarily for type 2 diabetes and, at higher doses, obesity. A person with type 1 diabetes cannot substitute a GLP-1 drug for insulin; the two classes are typically complementary, not interchangeable, in someone who needs both.