The cost of insulin has more than tripled in the last decade, and U.S. Sen. Amy Klobuchar says it's financially squeezing people with diabetes who rely on the drug to regulate their blood sugar.

The Democratic senator scheduled a news conference Sunday at Regions Hospital in St. Paul to call for congressional action.

"This is really hurting regular Minnesotans for no reason," Klobuchar said in a phone interview earlier in the day. "This is not a newly innovative drug. It is not something that's for a rare disease. It's one of the more common diseases in America."

In fact, roughly 29 million Americans have diabetes, including about 320,000 Minnesotans.

Klobuchar called for votes on bills she is pushing in Congress that increase competition by allowing Medicare to negotiate lower prices for prescription drugs, ease restrictions on importing drugs from Canada and increase the availability of generic drugs.

Klobuchar also co-authored a bill that would end the practice of brand-name drug companies paying to keep generic versions off the market.

"A lot of why we're seeing the rising prices is a lack of competition and the fact that the drug companies see a monopoly and they go for it," she said. "We just don't have a lot of competitive products."

Earlier this month, Klobuchar sent letters to the CEOs of three pharmaceutical companies: Eli Lilly, Sanofi and Novo Nordisk, pressing for an explanation. She wrote that the simultaneous price increases "raise questions about potential coordination."