More than 1 million Americans ration their insulin as the drug's cost skyrockets

About 1.3 million Americans rationed their prescribed doses of insulin last year to save money, a pattern one doctor said threatens the health — and even the lives — of people with diabetes. 

Many people are taking less than the recommended amount of insulin as the cost of the life-saving drug has soared in recent years, university researchers said in a new study published in the Annals of Internal Medicine. A survey revealed that more than 16% of diabetes patients who take insulin either skipped their prescribed doses, took less than needed or delayed buying more. 

"Insulin rationing is frequently harmful, and sometimes deadly," Adam Gaffney of Harvard Medical School, who co-authored the study, said in a statement.

The research marks "the first national estimate of how many Americans with diabetes are rationing their insulin now due to cost," said consumer advocacy group Public Citizen, which announced the study.

More than 37 million Americans have diabetes, according to the Centers for Disease Control and Prevention. Roughly a quarter of them use insulin, research has found. The average price of insulin rose 54% from 2014 to 2019, according to a GoodRX study published earlier this year. 

Nearly 20% of middle-income insulin users reported rationing their dosage, compared to 1 in 10 for those with higher incomes, the new study concluded. Diabetes patients who lack health insurance ration their insulin more often than those with Medicaid or private coverage, the researchers also found. 

Three companies — Eli Lilly, Novo Nordisk and Sanofi — dominate the insulin market in the U.S., and each company has raised its prices considerably since introducing their products more than two decades ago. Insulin analogs, which are synthetic versions of insulin, control blood sugar better than so-called human insulin, and represent more than 90% of the market, according to the American Action Forum, a center-right think tank.

Novo Nordisk's insulin drug costs $289 per vial, while Eli Lilly's and Sanofi's versions costs $275 and $276, respectively, according to an April report from Human Rights Watch. 

Moving to offer patients a cheaper option, Walmart said last year it would offer a private-brand insulin at $72.88 per vial. The insulin would be between 58% to 75% cheaper than other products on the market, said Walmart, who's insulin is made by Novo Nordisk.

The most common types of insulin cost 10 times more in the U.S. than in any other developed country, according to the Mayo Clinic.