Starting January 1, 2024, UnitedHealth’s (UNH:US) Optum Rx is implementing a significant change by designating eight preferred insulin products to tier one on standard commercial formularies.

This move aims to restrict out-of-pocket expenses for these insulin products to $35 or less, aligning with Optum Rx's ongoing commitment to enhancing access and affordability for critical medications.

Three manufacturers—Eli Lilly (LLY:US), Novo Nordisk (NVO:US), and Sanofi (SNY:US)—will have their products added to tier one.

As a result, shares of Eli Lilly and Novo Nordisk moved lower on Thursday.

Currently, over 70% of Optum Rx users pay less than $35 per month for insulin. With these recent changes by Optum Rx, it is anticipated that as of January 1, 2024, 98% of all Optum Rx consumers will have the opportunity to access insulin at a cost of $35 or less per month.

“I’ve seen firsthand how high prices for insulin and other necessary medications can cause patients to limit or skip doses,” said Dr. Patrick Conway, chief executive officer of Optum Rx.

“Medicine that people can’t afford is useless, and by taking this important next step to change our formulary, we will lower costs and improve access for more people who need this life-saving medication. Our goal is to make all essential medicines affordable.”

Eli Lilly and Novo Nordisk shares previously hit all-time highs amid robust demand for diabetes drugs like Ozempic and Wegovy.

Congress members Markwayne Mullin and Sheldon Whitehouse were buying LLY shares in September in accordance with the robust YTD performance. Mullin also purchased UNH shares in two transactions, valued up to $65,000.