Robert Newton has been taking insulin for years to keep his diabetes in check, but with the medication now costing him $500 a month, there are times when he has no choice but to ration his supply and take less than he should.

"I only get so much money a month," said the 65-year-old recent retiree. "It takes up almost half of the money that I get."

Newton's is the sort of story that no doctor wants to hear. But the price of insulin has more than tripled in the last decade, and now thousands of diabetics in Minnesota are struggling to afford the medication they need to keep their blood sugar under control.

A recent Star Tribune analysis of Medicare spending in Minnesota found that prices have soared for numerous widely used medications — including certain antibiotics, blood pressure drugs and insulin — because of limited competition and other factors.

In the case of insulin, quite apart from the financial burden, the stunning price increase has forced some diabetics into practices that can place their lives at risk and has left many doctors across the state worrying about their patients' health.

"They just stop taking it because they have to feed their children," said Dr. Lisa Fish, who cares for diabetics at Hennepin County Medical Center in Minneapolis. "But over time, they are at much increased risk in the short term for hospitalization and in the long term for kidney failure, blindness and amputation."

Not only has the price of insulin soared, but the costs of other drugs and supplies that diabetics need have also skyrocketed. Sometimes a supply of test strips that diabetics use for blood testing can run into the hundreds of dollars.

"It absolutely has gotten worse year after year," said Diane Alexander, pharmacy director at Children's Hospitals and Clinics. "It is very uncomfortable for us because we don't set the prices. We are caught between dispensing the drug and the patient who can't afford it."

Insulin is one of many widely used prescription drugs that were once affordable but have seen price increases far beyond the rising cost of production, according to consumer groups and physicians. A lawsuit filed in federal court in Massachusetts earlier this year alleged collusion among the three major insulin makers, noting that their list prices have climbed in near lockstep. The companies say that's not true and are challenging the charge in court.

Some elected officials, including U.S. Sens. Amy Klobuchar and Al Franken of Minnesota, have called for easing restrictions on drug imports from Canada and bringing generics to market faster.

The financial burden creates additional anxiety for patients coping with a stressful disease that requires constant daily monitoring.

Newton knows that he's taking risks when he rations insulin, but he tries to compensate by controlling his blood sugar by taking a longer walk and being careful about what he eats.

"I've done a lot of things in life," said Newton, who worked in the grocery business for many years. "This is by far the hardest thing I have ever had to do.

"The problem is that [diabetes] doesn't go away. You are always going to need insulin."

'You have to be more careful'

While low-income diabetics on Medical Assistance, Minnesota's Medicaid program, are often insulated from price increases because the program picks up most of the costs, seniors on Medicare can run into financial problems when they hit the "doughnut hole," or coverage gap, in drug coverage.

People on commercial insurance, especially those on high-deductible plans, not only have to make costly co-payments at the beginning of the year until their insurance kicks in, but are sometimes forced to change brands of insulin as insurance companies tinker with their lists of approved medications as part of cost-saving measures.

Changing insulin brands can turn a stable diabetic into one who needs more monitoring.

"You have to be more careful because you don't know if they are going to react badly to that one brand," said Dr. Dave Thorson at the Entira White Bear Lake clinic. "It may be saving the insurance company money, but it is costing the patient money because they have to come in for more visits."

For some patients, the bigger shock comes from rising prices of diabetic supplies.

Last January, Kim Battern of Plymouth went online to order a three-month supply of testing strips, which allow her to monitor her blood sugar. She found that the price had jumped from $80 to more than $200.

"I just turned the computer off. I thought it had to be a mistake," she said. "It was so shocking to me that with insurance that I would have to pay so much for these little strips."

Battern, 63, who recently retired, wonders how far prices will rise.

"You have to have it, or else you are going to die," she said. "You can see that the prices are jumping and where is it going to end?"

Battern said she feels lucky that she can afford the drugs and supplies for now, but even so she keeps some used pen injectors, which come preloaded with insulin doses: They have very small amounts of insulin left just in case she needs a small amount later.

"I don't throw them away, it is too precious," Battern said.

Older, less effective insulin

Across the Twin Cities, clinics and hospitals are trying to help patients who are struggling with the costs. Most manufacturers offer patient assistance programs, but they often have strict eligibility requirements. Discount coupons are also available, but they often can't be used by people on Medicare.

Some patients are encouraged to buy a cheaper, generic form of the older type of insulin, but physicians say it's not as effective as newer forms.

"Now we are having to teach people how to use the older insulins because so many people can't afford modern insulin," said Fish.

The resulting financial stress, doctors say, can actually compound the physical effects of diabetes.

"Stress can raise blood sugar levels and cause variability in blood glucoses," said Dr. Laura Gandrud, a pediatric endocrinologist at Children's. "It is an unbelievable burden in terms of the stress."

Shari Jackson Wiltrout of Cambridge has felt the burden ever since her 11-year-old daughter was diagnosed in 2015.

"It is more stressful to deal with the insurance companies and the bills than it is to manage the diabetes," she said.

But most of all, Wiltrout worries about the financial burden of diabetes for her daughter as she grows up and becomes independent.

"When she is paying off student loans and her first mortgage and all of that, how is she going to make it work?"

Glenn Howatt • 612-673-7192