Consumers whose drug benefits are managed by Express Scripts could see their out-of-pocket costs for insulin limited to $25 a month under a plan announced Wednesday.

The move is aimed at addressing rising anger over the cost of the lifesaving product, whose list price has skyrocketed in recent years. Express Scripts said about 700,000 people filed a claim for insulin last year through its Cigna or Express Scripts plans. The average monthly savings for those whose employers opted into the plan would be about $16 a month.

Insurers and drug manufacturers have been under pressure to show that they are doing something about the rising list price of drugs, in particular insulin, which many people with diabetes need to survive.

The average price of insulin, versions of which have been around since the 1920s, roughly doubled to about $450 a month in 2016 from around $234 a month in 2012, according to the Health Care Cost Institute. And the cost has risen even higher since 2016, putting people without insurance and those with high deductibles at risk of rationing their doses and, in some cases, going without treatment.

“For people with diabetes, insulin can be as essential as air,’’ said Dr. Steve Miller, executive vice president and chief clinical officer of Cigna, which merged last year with Express Scripts. “We need to ensure these individuals feel secure in their ability to afford every fill so they don’t miss one dose, which can be dangerous for their health.’’

Multiple congressional inquiries have focused on insulin, and Tuesday, a subcommittee of the House Energy and Commerce Committee held a hearing on insulin prices that featured testimony from patients and doctors. Executives from the top pharmacy benefit managers, including Express Scripts, are scheduled to testify before the Senate Finance Committee next week.

Senator Charles Grassley, a Republican of Iowa, the finance panel’s chairman, and Senator Ron Wyden, the panel’s ranking Democrat from Oregon, sent letters to Express Scripts and two other major drug benefit managers asking for more information about the role they play in rising insulin costs. “The essential question is whether the practices employed by PBMs actually reduce the cost of insulin for patients and achieve the lowest possible federal spending,’’ the senators said in their letter.

Under the new plan, employers who cover their workers through Cigna and Express Scripts can opt into the program. The extra costs will be picked up by the three drugmakers that sell insulin — Eli Lilly, Novo Nordisk, and Sanofi. Because the manufacturers are covering the costs, anti-kickback laws prohibit Medicare beneficiaries and other people insured through government health care programs from these types of negotiated arrangements.

Cigna and Express Scripts said the average out-of-pocket cost for consumers under their existing plans was $41.50 for a 30-day supply of insulin. (Another large pharmacy benefit manager, OptumRx, which is owned by UnitedHealthcare, cited similar costs.) The companies said that patients with a high deductible or coinsurance — where they must pay a percentage of a drug’s list price — would benefit the most.

But Elizabeth Rowley, founder and director of T1International, a diabetes advocacy group that does not accept drug-industry funding, said the new plan failed to address the underlying cause of the problem: high list prices.

“This is yet another P.R. move — a stopgap at best — to release the pressure on those responsible for the insulin price crisis,’’ she said in an e-mail Tuesday. “Those patients who are lucky enough to be on a ‘participating plan’ can benefit, but what about those who aren’t? This program gives no lifetime ‘assurance’ that people with Type 1 diabetes can rely on.’’

Insulin has come under particular scrutiny because of the growing gap between the list price — what someone without insurance would pay at a pharmacy — and the net price, or what insurers and employers pay when someone with diabetes is prescribed insulin through their plan.