The high price of medicine cost him his life.

When Josh Wilkerson turned 26, he aged out of his stepfather’s private health insurance and he was unable to afford his nearly $1,200-a-month insulin.

He began rationing his pricey prescription, before a doctor recommended taking ReliOn, an over-the-counter brand sold for $25 a vial at Walmart.

“It didn’t work for his body,” his mom, Erin Wilson-Weaver, tells The Post. Her son died June 14, and she’s still in mourning — but determined to advocate in his memory.

Known as “human insulin,” ReliOn requires more time to become effective than the “analogue” insulin that Wilkerson had previously been taking — but, at one-tenth of the price, it was more affordable for the northern Virginia dog kennel supervisor, who was earning $16.50 an hour.

“When it comes to type 1 diabetes, people are facing unthinkable decisions — between the costs of living and their very lives,” Wilson-Weaver writes in a post for a diabetes advocacy blog full of similar posts about those lost to Type 1 diabetes after being unable to afford insulin.

“We figured: Hey, it’s $25. We can do that, and we’ll just work with it and try to do the best we can,” Wilkerson’s fiancée, Rose Walters, 27, tells the Washington Post. Walters, also a Type 1 diabetic, began using the cheaper insulin as well last winter.

The pair also had to switch to an over-the-counter brand for their blood glucose meters to keep medical prices within their budget.

The couple — among the 30 million US residents living with diabetes — planned for a rustic barn house wedding in October, and hoped to save money for it with the more affordable medication, which can be less effective for some diabetics.

Wilkerson’s mom was concerned — she had lost her father to Type 1 diabetes complications when he was just 38, and this wasn’t the first time insurance complications had prevented Josh from getting the medical attention he needed.

Still, after graduating high school, Josh lost his childhood insurance coverage, and his troubles began. “He couldn’t afford the maintenance or supplies for his insulin pump, so he had to make the switch back to syringes,” Wilson-Weaver writes in a blog post. When his health care changed, “Josh’s health and life really began its downward spiral.”

When Wilson-Weaver told Josh she was worried, though, Wilkerson reassured her. “Don’t worry, mom,” he wrote her in a Facebook message after she sent him an article about a man who had died after rationing his insulin.

But she was right to worry: While Walters was fine, Wilkerson was experiencing stomach problems, mood swings and high blood sugar in response to the ReliOn.

In June, when Walters was staying overnight at the kennel for a week while his boss was away, his symptoms proved fatal.

On his second night sleeping there, Wilkerson and Walters were FaceTiming before bed when he complained of stomach problems but promised to take his insulin before signing off, WaPo reports. In the morning, when Walters called his phone and he didn’t pick up, she became worried. She rushed to the kennel to discover that Wilkerson was unconscious on the floor.

“I just remember smacking him on the face, saying, ‘Babe, wake up. You have to wake up,’” says Walters.

Wilkerson had suffered multiple strokes and was in a diabetic coma, his blood sugar 17 times what’s considered normal. “The staff at the hospital had never seen a blood glucose reading as high as Josh’s before,” says Weaver-Wilson.

He died five days later. He was 27.

“The saddest thing was, when he was diagnosed, and until he was 18, his insurance provided him the best and newest care available,” Wilson-Weaver says, calling his death “absolutely” preventable.

His death illustrates the worst-case scenario for thousands of people living with diabetes in the US, the Independent reports. With analogue insulin prices nearly tripling since 2002, doctors have begun recommending the cheaper version as a stopgap — a strategy endorsed for “some patients” by the American Diabetes Association.

During the government shutdown in January, one federal worker was also forced to ration her insulin, living through the extreme fear and discomfort as she could no longer afford her copay for more.

In May, the governor of Colorado signed legislation capping insurance co-payments on insulin to $100 a month to prevent such tragic fates as Wilkerson’s.

Last month, the Trump administration announced it will create a way for Americans to legally import lower-cost prescription drugs from Canada.

In the near future, scientists may even be able to replace insulin altogether for those with Type 1 diabetes: Researchers are rapidly working toward creating insulin-producing cells, essentially curing the disease.