There is no single expiration date for insulin patents. Each brand-name insulin is protected by a stack of overlapping patents covering the molecule, the manufacturing process, the formulation, and the delivery device, and those patents expire at different times. The practical picture in 2026: older insulins like Lantus and Humalog have lost enough protection that biosimilar and generic versions are already on pharmacy shelves, Novolog gained its first biosimilar competitors in 2025, and Tresiba remains protected into the 2030s.
Why One Insulin Has Dozens of Expiration Dates
A U.S. utility patent runs 20 years from the date the application was filed.1Office of the Law Revision Counsel. 35 U.S. Code 154 – Contents and Term of Patent; Provisional Rights But manufacturers rarely rely on one patent. A study of FDA-approved insulin products found that the median number of pre-approval patents per product rose from zero in 1986–1996 to 17 in 2008–2019, and that patents filed after FDA approval added a median of six more years of protection for nine of the products studied.2National Library of Medicine. Patents and Regulatory Exclusivities on FDA-Approved Insulin Products
Delivery devices drive much of that stack. Sixty-three percent of all patents on the insulins studied covered devices like pens and auto-injectors, and 85 percent of those device patents never mentioned insulin in their claims.2National Library of Medicine. Patents and Regulatory Exclusivities on FDA-Approved Insulin Products A pen patent that says nothing about insulin can still block a competitor from selling a biosimilar in that pen format. Device patents extended market protection beyond other patents by a median of 5.2 years. This layering of new patents onto existing products is often called evergreening.
Patent Status of the Major Insulin Brands
Lantus (Insulin Glargine)
Sanofi’s Lantus, approved in 2000, had 74 U.S. patent applications filed on it, and 95 percent of those were filed after the drug reached the market. The expected span from first approval to last-expiring patent was 32.9 years, the longest of any insulin product studied.2National Library of Medicine. Patents and Regulatory Exclusivities on FDA-Approved Insulin Products Competitors challenged enough of that wall to bring alternatives to market anyway. Eli Lilly’s Basaglar launched at the end of 2016 after a patent settlement, and two interchangeable biosimilars followed, Semglee and Rezvoglar, both in 2021. Semglee was discontinued at the end of 2025, but Basaglar, Rezvoglar, and generic insulin glargine from Winthrop and other manufacturers remain available.
Humalog (Insulin Lispro)
The compound patent on Eli Lilly’s Humalog, approved in 1996, has expired in major markets. Sanofi’s follow-on insulin lispro product Admelog was approved in December 2017, and Lilly launched an authorized generic in 2019 at a 50 percent lower list price, with a single vial listed at $137.35.3Eli Lilly and Company. Lilly to Introduce Lower-Priced Insulin Some device and formulation patents may still cover specific pen configurations.
Novolog (Insulin Aspart)
Novo Nordisk’s Novolog had an expected protection span of 32.3 years from first approval to last-expiring patent.2National Library of Medicine. Patents and Regulatory Exclusivities on FDA-Approved Insulin Products Competition arrived in 2025. Sanofi’s Merilog, the first biosimilar to Novolog, was approved in February 2025, and Biocon/Viatris’s Kirsty, the first interchangeable biosimilar, was approved in July 2025.4U.S. Food and Drug Administration. New Drug Therapy Approvals 2025 Because Kirsty is interchangeable, a pharmacist can substitute it for Novolog without a new prescription.
Tresiba (Insulin Degludec)
Novo Nordisk’s ultra-long-acting Tresiba is still protected. Key patents are not expected to expire until at least the mid-2030s, biosimilar filings are only in early stages, and no biosimilar insulin degludec is expected on the U.S. market before 2030 at the earliest.
Why Expiration Finally Opened the Door in 2020
Until 2020, insulin was regulated as a drug under the Federal Food, Drug, and Cosmetic Act. On March 23, 2020, insulin products transitioned to regulation as biological products under the Public Health Service Act, which opened insulin to the biosimilar approval pathway for the first time.5U.S. Food and Drug Administration. FDA Works to Ensure Smooth Regulatory Transition of Insulin and Other Biological Products Under 42 U.S.C. § 262(k), a manufacturer can file an abbreviated application by showing the product is highly similar to an approved reference biologic with no clinically meaningful differences in safety, purity, and potency.6Office of the Law Revision Counsel. 42 U.S. Code 262 – Regulation of Biological Products Products meeting higher standards can be designated interchangeable, allowing pharmacist substitution without calling the prescriber.7U.S. Food and Drug Administration. Interchangeable Biological Products
Why Expired Patents Haven’t Automatically Lowered Prices
Even after patents expire and biosimilars arrive, insulin prices don’t fall the way generic pill prices do. Pharmacy benefit managers, the middlemen who negotiate drug prices between manufacturers and insurance plans, earn revenue through rebates and fees calculated as a percentage of a drug’s list price. Higher list prices generate larger rebates. According to the Federal Trade Commission, when lower-priced insulins became available, PBMs systematically excluded them from insurance formularies in favor of higher-priced, heavily rebated alternatives, producing what the agency called an upside-down market where manufacturers raised list prices to compete for formulary placement.8Federal Trade Commission. FTC Sues Prescription Drug Middlemen for Artificially Inflating Insulin Drug Prices
The FTC filed an administrative complaint against the three largest PBMs in September 2024. In February 2026 it secured a settlement with Express Scripts requiring changes to its business practices, with projected savings of up to $7 billion over ten years.9Federal Trade Commission. Caremark Rx, Zinc Health Services, et al., In the Matter of (Insulin) Proceedings against the remaining PBM respondents are ongoing.
What Actually Determines Your Price Today
Regardless of where any patent stands, several protections have already reduced what many people pay at the counter.
All three major manufacturers cut list prices effective January 1, 2024. Sanofi reduced Lantus by 78 percent and Apidra by 70 percent.10Sanofi. Sanofi Cuts U.S. List Price of Lantus, Its Most Widely Prescribed Insulin Novo Nordisk lowered NovoLog and NovoLog Mix 70/30 by 75 percent and Levemir by 65 percent, bringing a NovoLog vial to $72.34.11Novo Nordisk. Novo Nordisk to Lower U.S. Prices of Several Pre-Filled Insulin Pens and Vials up to 75% Eli Lilly caps out-of-pocket costs at $35 per month through its Insulin Value Program for people with commercial insurance or no insurance, alongside broader list price reductions.12Eli Lilly and Company. Lilly Insulin Access People enrolled in federal insurance programs like Medicare are not eligible for the Lilly program, but separate federal rules cover them.
Starting in 2023, the Inflation Reduction Act capped out-of-pocket insulin costs for Medicare Part D beneficiaries at $35 per month per covered insulin product.13Centers for Medicare and Medicaid Services. Anniversary of the Inflation Reduction Act: Update on CMS Implementation The same law set a broader annual out-of-pocket cap for all Part D prescriptions: $2,000 in 2025, rising to $2,100 in 2026.
More than half of U.S. states, plus the District of Columbia, have capped insulin copayments in state-regulated commercial insurance plans. Monthly caps range from $0 in New York to $100 in states like Colorado and Alabama, with most settling at $25 to $35 per 30-day supply. These laws do not apply to self-insured employer plans, which are regulated under federal law, so what you pay depends on your plan type.
If you use Lantus, biosimilars exist and the brand itself now lists at 78 percent below its 2023 price. If you use Novolog, the first interchangeable biosimilar arrived in 2025 and your pharmacist may be able to substitute it without a new prescription. If you use Tresiba, biosimilar competition is a 2030s question. Whichever insulin you take, check your state’s copay law, your manufacturer’s savings program, and whether the $35 Medicare cap applies to you. Patent expiration shapes the long-term market; those shorter-term protections shape what you actually pay this month.