As the new Congress looks for ways to address high drug prices, two prominent lawmakers asked Eli Lilly, Novo Nordisk and Sanofi to explain the soaring prices of their insulin products.

The prices “have skyrocketed in recent years,” putting the drug out of reach for many patients, said Rep. Frank Pallone (D-N.J.), chair of the Energy & Commerce Committee, and Rep. Diana DeGette (D-Colo.), chair of the Oversight and Investigations Subcommittee, in a letter to the drugmakers.

The two representatives asked the companies what they believe are the root causes of the rising prices and what’s preventing them from making the drug more affordable. They also grilled the companies on any agreements made in the last decade that make it harder — or impossible — for generic versions of insulin to compete in the marketplace, requesting copies of any deals that were made.