The FDA approved Garzulys, an insulin aspart biosimilar, adding another entrant to the competitive landscape that is slowly deflating insulin list prices. The approval marks the latest step in the biosimilar wave that has been building since the Inflation Reduction Act's insulin cap provisions took effect. [1]
The regulatory context frames what kind of approval this is. Insulin aspart — the rapid-acting analog taken by millions at mealtimes — came off its last major patent protections years ago, and each subsequent biosimilar approval is less a scientific event than a manufacturing credential: the FDA confirming that a second or third producer can match the reference product's pharmacokinetics within tight tolerances. The agency's designation of Garzulys as interchangeable matters more than the approval itself, because interchangeability is what lets a pharmacy substitute it without prescriber reauthorization — the difference between theoretical and actual competition.
The gap between the announcement's routine framing and the structural shift it represents is the divergence. Each new biosimilar entry increases competitive pressure on list prices — but the diabetes community on X treats the approvals as incremental rather than transformative, citing PBM rebate structures that blunt the price competition's impact on out-of-pocket costs. [1]
Where Competition Gets Intercepted
For patients, the question is whether the growing biosimilar market translates into lower copays or simply generates rebate revenue for pharmacy benefit managers. The list-price reductions that biosimilar competition produces may not reach the patients who need them most if the rebate system intercepts the savings. [1]
The interception mechanics are worth spelling out, because they explain why seven insulins competing has not produced seven cheap insulins for everyone. Formulary placement is purchased with rebates; incumbents protect share by paying larger rebates on higher list prices; a biosimilar entering at a genuinely low list price cannot pay a large rebate from a small margin, so formularies keep the high-list-high-rebate incumbent and the cheap vial stays off the preferred tier. The patient with a high-deductible plan never touches the rebate stream at all — their out-of-pocket cost tracks the list price they cannot get. The system's defenders note the $35 Medicare cap now floors seniors' exposure regardless of list mechanics, which is true and beside the point for the insured working-class diabetic whose copay is set by the very intermediaries the competition was supposed to discipline. [1]
There is also a quieter macro effect the approval accelerates. As interchangeable biosimilars accumulate, Medicare's negotiated price references shift downward, which disciplines the category's net prices even where formulary games persist — the one lever the IRA created that operates upstream of PBM discretion. Each approval like this one slightly rewrites the negotiation baseline for every insulin that follows it into the room.
The approval is one data point in a larger trend: the insulin market is becoming more competitive at the manufacturing level while remaining opaque at the patient level. Garzulys enters a market where the supply side is increasingly crowded but the pricing side remains governed by intermediaries rather than competition. [1]
The next receipt to watch is not another approval but a formulary filing — which plans put Garzulys on their preferred tiers for 2027, and at what negotiated net cost. Biosimilars have won every contest about molecules. The contest that determines what diabetics actually pay happens in contract language nobody live-tweets, between three companies most patients cannot name.