A recent study in the Journal of the American Medical Association said the price of insulin nearly tripled between 2002 and 2013, and three manufacturers -- Sanofi, Novo Nordisk and Eil Lilly -- have raised the list prices of their insulin in near unison, The New York Times reported.
The price increases have triggered anger among patient groups and doctors, who say the rising cost of insulin appears to have little to do with higher production costs.
"People who have to pay out of pocket for insulin are paying enormous prices, when they shouldn't be," Steve Berman, a lawyer for the patients, told The Times.
The lawsuit alleges that the three companies increased the list prices on their insulin in order to win favor with pharmacy benefit managers, who team with drug makers and health insurers to determine how a drug will be covered on a list of approved drugs.
While benefit managers are complicit, the lawsuit targets the drug makers because "they are playing the game, and they are the ones who publish the list price," Berman said.
Representatives for the three drug companies could not immediately be reached for comment, The Times reported.
The lawsuit includes several examples of diabetes patients who can't afford the up-to-$900 cost of their insulin and have resorted to using expired insulin or starving themselves to control their blood sugar.