Insulin shortages stem from a combination of manufacturing delays, product discontinuations, an extremely concentrated market, and ongoing access barriers that leave many patients unable to get the insulin they need. The problem isn’t a single cause but rather a fragile supply system where small disruptions create outsized consequences for people who depend on insulin to survive.
A Fragile Manufacturing System
Only three companies supply insulin to patients in the United States: Novo Nordisk, Sanofi, and Eli Lilly. Together, they control over 90 percent of the global insulin market. When any one of them hits a production snag, there’s very little slack in the system to absorb it.
That’s exactly what happened in early 2024, when Eli Lilly warned that two of its insulin formulations would be temporarily out of stock. The company cited “a brief delay in manufacturing” combined with the “dynamic nature of insulin supply and demand.” Specifically, 10-milliliter vials of Humalog and its generic equivalent were in short supply at wholesalers and pharmacies, though prefilled pen versions remained available. For patients who rely on vials, particularly those using insulin pumps or those whose insurance covers vials but not pens, the distinction mattered enormously.
Lilly also discontinued its 3-milliliter vials entirely, saying it would “help create greater supply resiliency and product availability by streamlining production and distribution processes.” In practice, streamlining production means fewer product formats on the manufacturing line, which can improve efficiency for the manufacturer but reduces options for patients and pharmacies.
Products Being Phased Out
Some shortages aren’t temporary disruptions. They’re permanent. Novo Nordisk is discontinuing Levemir, a long-acting insulin that many people with Type 1 and Type 2 diabetes have used for years. Levemir FlexPen and Penfill products will no longer be available after December 2026, and no version of this insulin is expected to remain on the market from 2027 onward. Novo Nordisk has said the discontinuation is part of a global strategy and is unrelated to safety, quality, or effectiveness. That’s cold comfort for patients who have been stable on Levemir and now need to transition to a different long-acting insulin, navigating new insurance approvals and potential differences in how their body responds.
The Weight Loss Drug Question
Both Eli Lilly and Novo Nordisk now make blockbuster weight loss and diabetes drugs in the GLP-1 class. It’s a reasonable question: are these companies diverting manufacturing resources away from insulin to produce more profitable products? Lilly has stated directly that it does not prioritize GLP-1 drug manufacturing over insulin and that demand for those drugs is not impacting insulin supply. A Lilly spokesman also said the 2024 insulin shortage was unrelated to its GLP-1 products.
Whether or not there’s a direct manufacturing conflict, the business incentives are hard to ignore. GLP-1 drugs generate enormous revenue. Insulin, especially with new price caps and generic competition, is far less profitable. When a company is making strategic decisions about which product lines to invest in and which to streamline, the financial pressure to focus on higher-margin products is real, even if it doesn’t show up as a factory being repurposed overnight.
Why Competitors Can’t Easily Fill the Gap
In most industries, a shortage from one manufacturer would be an opportunity for competitors to step in. Insulin doesn’t work that way. It’s a biologic, meaning it’s produced by living cells rather than synthesized chemically. The final structure of the insulin molecule depends heavily on the exact manufacturing process used, and those processes are protected as trade secrets. A competitor can’t simply copy the recipe. Developing a biosimilar insulin requires independently recreating a complex biological manufacturing process, which is expensive, time-consuming, and technically difficult.
This is why, despite insulin being discovered over a century ago, the market remains dominated by three companies. The barriers to entry are enormous. Even though insulin could be sold at much lower prices and still yield profits, the market control of the existing manufacturers makes it extremely hard for a new company to gain a foothold. The result is a supply chain with very few backup options when things go wrong.
Rationing Remains Widespread
The consequences of this system fall directly on patients. A 2024 study published in the Journal of General Internal Medicine found that nearly 38 percent of insulin users reported rationing their insulin due to cost, insurance delays, or pharmacy shortages. About 24 percent rationed specifically because of cost, 17 percent because of insurance delays, and nearly 19 percent because their pharmacy simply didn’t have it in stock.
Perhaps most striking: the rate of cost-related rationing in 2024 was statistically unchanged from 2017, despite years of public pressure, legislative action, and voluntary price cuts from manufacturers. The $35 monthly copay cap that took effect for Medicare patients hasn’t solved the problem for everyone, particularly for uninsured patients and those on high-deductible plans who still face the full list price before their coverage kicks in.
Rationing insulin is dangerous. People who skip doses or use less than prescribed risk dangerously high blood sugar, which over time damages the kidneys, eyes, nerves, and heart. In acute cases, running out of insulin can lead to diabetic ketoacidosis, a life-threatening emergency.
Cross-Border Purchasing Strains Supply Elsewhere
American patients seeking affordable insulin have increasingly turned to buying it from Canadian pharmacies, where the same products cost a fraction of U.S. prices. This has created a secondary shortage problem: pharmacies in Canadian border towns have reported limited insulin supplies after bulk purchases by Americans crossing the border. If legalized insulin importation were to scale up, analysts warn it could disrupt supply chains in other countries, potentially raising prices and reducing access for patients outside the U.S.
What This Means for Patients Right Now
If you’re having trouble finding your insulin at the pharmacy, the issue likely traces back to one or more of these factors: a temporary manufacturing delay for your specific product format, a permanent discontinuation that’s reducing available options, or distribution bottlenecks at the wholesale level. Prefilled pens are generally more available than vials, so asking your pharmacist or prescriber about switching formats can sometimes resolve an immediate shortage. If your specific insulin is being discontinued, your prescriber will need to transition you to an alternative, which may require prior authorization from your insurance.
For patients using Levemir, the clock is ticking toward a December 2026 cutoff. Starting that conversation with your healthcare provider sooner rather than later gives you more time to find an alternative that works well for your body and is covered by your plan. Biosimilar insulins do exist, though the options remain limited compared to what the market needs. As long as three companies control over 90 percent of global insulin production, the system will remain vulnerable to exactly the kind of shortages patients are experiencing now.