Harris County filed a lawsuit Thursday against three insulin manufacturers and four pharmaceutical benefit managers claiming they worked together to raise the costs of insulin and other diabetic treatments.

The suit names the three largest manufacturers of insulin —Eli Lilly, Novo Nordisk and Sanofi — and the largest pharmaceutical benefit managers — Aetna Rx, CVS Caremark, Express Scripts and OptumRx.

The county hopes to recover the $27.5 million it has already paid and hold the companies accountable.

“We are bringing this lawsuit to hold these billion-dollar companies responsible for conspiring to drive up the prices of their life-saving insulin for our residents while securing record profits for themselves,” said Harris County Attorney Vince Ryan.

Harris County provides insurance for its 38,000 employees, their families and the inmates at the county jail.

In 2015, the county claims the amount it spent on diabetes medications increased more than 60% from the previous year.

“Over the last fifteen years, the lawsuit alleges that these insulin manufacturers have in lockstep raised the reported prices of insulin in an astounding manner,” Harris County officials wrote in a press release. “Insulin sold for $20 per vial in the late 1990s. That very same insulin—which currently costs only $5 to produce—now sells for between $300 and $700.”

The county attorney said if it’s happening in Harris County, it’s happening elsewhere.

“We anticipate that we won’t be the only people suing the pharmaceutical companies and their benefit managers. The pharmaceutical benefit managers are the ones who manage the claims they’re given in the requests for the various drugs, so we got the managers conspiring with the manufacturers to gouge the public,” said Ryan.

Harris County officials say they’re prepared for a long, drawn-out process that they said could take years to conclude.