At a recent rally on the steps of the State Capitol, dozens of Minnesotans braved freezing winter temperatures to speak out for themselves and for the millions of other Americans with diabetes who find themselves in a life-and-death struggle to afford insulin, the only medicine that keeps them alive.

Joining them that day was a Minnesota mother, whose diabetic son died because the skyrocketing price of insulin forced him to ration his supply after he lost his insurance. She and others at the rally want their elected representatives to understand that for the 7.5 million people with diabetes in the United States who rely on insulin, the medication is not a choice, it's a matter of survival.

But most of all, they want action. At a hearing following the Capitol rally, State Rep. Laurie Halverson-who has diabetes herself-put it this way: "Insulin is air to a person with diabetes. If you don't have access to your insulin, you don't get to live."

With just three insulin manufacturers in the United States-Eli Lilly, Sanofi, and Novo Nordisk-this multi-billion dollar oligopoly has the market power to set insulin prices and reap huge profits in the process.

And prices have been skyrocketing. According to the American Diabetes Association, the average list price for insulin went up 300 percent between 2002 and 2013. Since then, an increasing number of people with diabetes are finding that ever-rising prices outstrip their ability to pay. The price tag can be hundreds of dollars in out-of-pocket costs each month, even for those with health coverage. For low-income Americans, or those without insurance, it's even worse.

As a member of the U.S. Senate Health Committee, I've met with that mother who lost her son. And I've worked with Minnesotans who are frustrated and angry when they discover that they pay 10-to-18 times more for insulin than people with diabetes pay in other countries. That is just wrong.

Insulin Not a New Drug

Insulin is not a new drug. It was discovered in Canada back in 1921 and quickly became a lifesaver for people with diabetes around the world. The researchers who discovered it were awarded the Nobel Prize. They sold the patent to the University of Toronto for just $1 because large profits were not their motive. Unfortunately, for millions of people with diabetes today, the three large insulin makers have a different motive.

Usually, a drug that has been around for nearly a century loses its patent and its price drops dramatically. However, incremental changes to the drug over decades, have allowed the three manufacturers to maintain lucrative patents and take older formulations off the market. Thus, 98 years after insulin's discovery, there is still no inexpensive supply of this lifesaving drug available in the United States.

Increasing Transparency on Skyrocketing Prices

Like the Minnesotans who raised their voices at the State Capitol, I've joined forces with several Senate colleagues in Washington, D.C. to put public pressure on the three insulin manufacturers to lower prices. We've pressed company executives to explain the reasons behind the recent spikes in insulin prices and we're pushing for them to be more transparent on how they set prices. We also want to know how those prices are affected by rebates the companies negotiate with the pharmacy benefit managers, who administer prescription drug plans for insurers and employers.

Beyond that, I'm helping to lead a bipartisan effort get the Food and Drug Administration to revise its recent "generic" insulin approval policy to ensure lower-cost insulin competitors come to the market sooner rather than later.

In the coming weeks, I plan to re-introduce my "Affordable Medications Act," a comprehensive bill to bring down the price of insulin and other prescription drugs. It would promote competition by reducing the time brand name companies can keep lower-cost insulin off the market.

Public Pressure Having an Impact

The work we're doing in Congress and the public pressure from diabetes advocates across the country may finally be having an impact. Recently, Eli Lilly announced it will soon offer a half-priced insulin product. Although this move has taken far too long, and the product is still far too expensive, I hope it will spur other actions to bring down prices, and bring health care to people with diabetes who can't live without insulin.

One thing is clear to me-and to those who rallied at the State Capitol: the health and well-being of millions of people in Minnesota and across the country should not depend on the profit-driven decisions of insulin makers with near-monopoly power.

Our voices are strong, but only if we use them. I'll keep fighting for people with diabetes until they have access to affordable insulin.