The CEOs of three major insulin makers are set to testify Wednesday during a U.S. Senate committee hearing on making the life-saving drug more affordable.

Sen. Bernie Sanders, who is chair of the Senate Health Education Labor and Pensions (HELP) Committee, is leading the charge against drug companies, calling on them to lower their prices.

The CEOs of Eli Lilly, Norvo Nordisk and Sanofi, which together control about 90% of the U.S. insulin supply, are expected to roll out their plans to make insulin more affordable. Lawmakers will also hear from pharmacy benefit managers (PBMs) from CVS Health, Express Scripts and Optum RX.

In statements shared ahead of the hearing, the drug companies appear to place the blame on PBMs for high patient out-of-pocket costs.  

PBMs negotiate with drugmakers for rebates and lower fees on behalf of employers and other clients and reimburse pharmacies for prescriptions they dispense. Each side blames the other for high drug prices.

Around 8.4 million of the 37 million people in the United States with diabetes use insulin, according to the American Diabetes Association.

Eli Lilly and Co. capped its out-of-pocket costs at $35 per month for those with or without insurance for an insulin prescription, according to the American Diabetes Association.

Novo Nordisk committed to reducing wholesale prices for several types of insulin, by 65 to 75% by January 2024. Sanofi also announced it would cut prices of its most commonly prescribed insulin product by next January.

While the details of the insulin price reduction plans for these companies are being fleshed out Wednesday, Sanders and Senate Majority Leader Chuck Schumer are also weighing two separate proposals that would cap the cost of insulin at $35 for both the insured and uninsured. One of those two could come up for a vote this month.