By Stephanie Stahl

PHILADELPHIA (CBS) — Some pharmaceutical companies have pledged to try to contain high prices of insulin, but patients with diabetes are still waiting for relief. During contentious hearings, insulin makers indicated to Congress that they would work to hold or lower prices.

It’s an issue for more than 7 million diabetics. Many are having trouble paying for the medication they need to stay alive.

Brayden Mertens, along with his brother and sister, have learned to live with Type 1 diabetes. Insulin to control blood sugar has become their life blood.

“In order to survive, they’re dependent on it with their lives,” mother Corinne Mertens said. “They have to have insulin injected into them. It’s really not a choice, you can’t just stop.”

Mayor Kenney: Safety Concerns Must Be Addressed Before Safe-Injection Site Established In Kensington

But to afford the life-saving drug, their mother says the family has had to make sacrifices.

“We get them in vials of insulin, and depending on your plan, that vial can range from about $250 to $500,” Mertens said. “You could use one to three vials a month, so you can add up with the math. It’s thousands of dollars.”

One recent study says the cost of insulin in the U.S. has nearly doubled over five years, from about $2,800 annually in 2012 to roughly $5,700 in 2016.

“People are dying from lack of access to a drug that’s been around for almost a century. I think it’s unconscionable,” said Dr. Kasia Lipska, of the Yale School of Medicine.

Drugmakers say they’re taking steps to address prices. Still, just three companies control 99% of the market and no generic version of the drug exists.

Regularly Exercising Can Help Control Symptoms Of Parkinson’s Disease, Researchers Say

The Mertens say, so far, they’re still able to afford insulin. But around the country, it’s a different story.

Prices have gotten so high, another study says one in four people with diabetes admitted to using less insulin than prescribed because of the cost.

Most insulin makers are now offering assistance programs to help patients who can’t afford their medication.

Stephanie Stahl