EXPLAINER: Why is insulin so expensive and difficult to cap?

Washington (AP) — Reining in the soaring prices of insulin has thus far been elusive in Congress, although Democrats say they'll try again — as part of their

The price of the 100-year-old drug has more than tripled in the last two decades, forcing the nation's diabetics to pay thousands of dollars a year for the life-saving medication. Democrats are considering capping the cost of that drug for at least some, although it’s unclear what the final proposal will look like and how many insulin users will get a price break.

Here’s a look at how insulin became so expensive and why it’s so difficult to bring the price of the drug down.

HOW MANY PEOPLE IN THE U.S. USE INSULIN AND FOR WHAT?

Roughly 8.4 million Americans use insulin, according to the American Diabetes Association. Not everyone who has diabetes needs insulin, but for those who do, it's an important medication. For more than 1 million of those people with type 1 diabetes, regular access to the medication is a necessity and they will die without it.