Most insulin used today is made by genetically engineered microorganisms, primarily bacteria and yeast, then sold through pharmacies, mail-order services, and increasingly through direct-to-consumer delivery programs. Three companies produce nearly all of it: Novo Nordisk, Eli Lilly, and Sanofi, which together control 96% of the global insulin market by volume.
How Modern Insulin Is Made
Until the 1980s, insulin came from the pancreases of pigs and cattle. That era is essentially over. Today’s insulin is produced using recombinant DNA technology: scientists insert the human gene for insulin into microorganisms, which then produce the protein in large fermentation tanks. About half the world’s pharmaceutical insulin is made by a yeast called Saccharomyces cerevisiae (the same species used in baking and brewing). The other half comes from engineered strains of E. coli bacteria. The resulting insulin is chemically identical to what a healthy human pancreas produces, or it’s slightly modified to act faster or last longer in the body.
Engineers continue to refine the yeast-based process by adding temporary structural elements to the insulin molecule that improve how efficiently the yeast produces it. These elements are removed during purification. The goal is higher yields from smaller batches, which lowers both production costs and environmental impact.
Animal-sourced insulin, particularly from pigs, still exists on a limited basis. It remains available in Canada and a few other countries for the small number of people who respond better to it. In the United States, it has largely disappeared from the market.
Where Patients Actually Buy It
Most people with diabetes get their insulin through a standard retail pharmacy with a prescription. The insulin travels from the manufacturer through wholesalers and distributors to the pharmacy, staying refrigerated throughout the supply chain. Your pharmacist dispenses it as vials, prefilled pens, or cartridges depending on the product and your prescription.
Mail-order pharmacy has become a major channel. Eli Lilly now runs a program called LillyDirect that ships its insulin products (Humalog, Humulin, Basaglar, and Lyumjev) directly to patients’ doors through licensed third-party pharmacies, including Amazon Pharmacy. Delivery typically takes one to four days, with same-day delivery available in some metro areas. Medications that require refrigeration won’t ship near holidays or weekends to avoid temperature problems in transit. Novo Nordisk and Sanofi offer similar mail-order options through various pharmacy partners.
A lesser-known option: older-generation insulins are available without a prescription at pharmacies including Walmart and CVS. These over-the-counter products include regular (short-acting) insulin, NPH (intermediate-acting) insulin, and a 70/30 premixed version. Walmart sells its own brand, ReliOn, made by Novo Nordisk, for as little as $25. Eli Lilly sells equivalent products under the Humulin name. These insulins are kept behind the pharmacy counter, so you need to ask a staff member for them directly. They work, but they’re older formulations that act more slowly and less predictably than modern rapid-acting and long-acting insulins, which makes dosing trickier.
What They Cost Now
Insulin pricing in the U.S. shifted dramatically in 2023 and 2024. All three major manufacturers announced steep price cuts within months of each other. Eli Lilly dropped the list price of its most commonly used insulins by 70% and capped out-of-pocket costs at $35 per month for people with private insurance who use participating pharmacies. Sanofi cut the list price of Lantus, its most prescribed insulin, by 78% and set the same $35 monthly cap for privately insured patients. Novo Nordisk slashed list prices on several popular pens and vials by up to 75%.
These caps apply to insured patients. For uninsured people, the picture varies by manufacturer and program, though each company runs patient assistance programs with different eligibility requirements.
Biosimilars and State-Led Programs
Biosimilar insulins are newer products that are near-identical copies of existing brand-name insulins, approved through a regulatory pathway similar to how generic drugs work for simpler medications. The FDA has approved biosimilar versions of NovoLog (insulin aspart), with products called Kirsty and Merilog reaching the market in 2025. These create competition that puts further downward pressure on prices.
California launched a more ambitious experiment. Through its CalRx initiative, the state partnered with the nonprofit manufacturer Civica Rx and Biocon Biologics to produce insulin glargine (a long-acting insulin) under a state label. CalRx insulin glargine pens became available at $55 for a five-pack of 3 mL pens starting January 1, 2026. The state had originally allocated $50 million for an in-state manufacturing facility, but that funding was cut due to budget constraints. Civica continues working independently on producing insulin glargine vials and pens under the CalRx label and is engaging with the FDA on quality testing.
The Three Companies Behind Nearly All of It
The concentration of the insulin market is striking. Eli Lilly (headquartered in Indianapolis), Novo Nordisk (based in Denmark), and Sanofi (based in France) control 99% of the global insulin market by value. This near-total dominance has persisted for decades, and it’s the primary reason insulin pricing became such a flashpoint. Each company produces multiple insulin formulations covering the full range of needs: rapid-acting for mealtimes, long-acting for background coverage, and premixed versions for simpler regimens.
Civica Rx, the nonprofit behind the CalRx partnership, represents one of the first serious attempts to break into this market from outside the big three. Biosimilar manufacturers are another route, though so far their products are still modeled on the originals made by these same companies. The practical reality for most people with diabetes is that your insulin, regardless of where you buy it or what you pay, almost certainly originates from one of these three manufacturers or their direct biosimilar competitors.