Why insulin makers cut list prices: the Medicaid rebate math turned on them

On March 14, 2023 Novo Nordisk announced it would cut list prices on several insulins — Levemir, Novolin, NovoLog, NovoLog Mix 70/30 — by up to 75% by year's end: a NovoLog vial would drop from $289.36 to $72.34, a NovoLog Mix 70/30 FlexPen from $558.83 to $139.71. Eli Lilly had made a similar announcement at the start of the month, and Sanofi, the third major US insulin maker, was expected to follow. A 2018 analysis had found US insulin list prices five to ten times higher than in other high-income countries — nearly $100 per standardized unit against production costs generally under $10.

The visible explanations were years of public backlash over price gouging and the Inflation Reduction Act of 2022, which capped Medicare Part D patients' out-of-pocket insulin at $35 a month; Lilly paired its cuts with a $35 monthly cap for commercial and uninsured patients too.

But health policy experts and lawmakers pointed to an older law as the real driver: the American Rescue Plan of 2021 eliminated the cap on the rebates drug companies owe Medicaid, effective January 1, 2024 — the same date the insulin price cuts fully kick in. Uncapped, the rebate formula could require insulin makers to pay Medicaid programs more than the price of their insulin every time Medicaid filled a prescription, likely totaling tens of millions of dollars.

The arithmetic: under the Medicaid Drug Rebate Program, a brand drug's basic rebate is the greater of 23.1% of the average manufacturer price or the gap between that price and the best market price — and on top sits the inflation penalty, which claws back every price rise above inflation measured against a decades-old baseline. For a drug priced at ten times its peers, an uncapped penalty scales past the sticker price itself.

The inflation-rebate penalty is proportional to how far list prices have outrun their baseline, and insulin's baseline was set before years of steep hikes.

Once the cap came off, each Medicaid script of high-list insulin could generate a rebate larger than the revenue it brought in — volume turned from profit into liability.

The cap's removal had a fixed start date, January 1, 2024, so repricing before then cleanly avoided the exposure.

The IRA's $35 Medicare cap and the backlash narrative gave the cuts a patient-friendly framing while the rebate math did the forcing.

When a penalty scales with a number you control, reprice the number — the uncapped rebate did in one law what a decade of public outrage couldn't.

The Novo Nordisk and Eli Lilly cuts were timed to land fully by January 1, 2024, exactly when the uncapped rebates began; Sanofi was expected to match. The episode re-priced insulin vials from roughly $290 to $72 and handed the companies a public-relations win for a move the rebate formula had effectively ordered.