The U.S. Federal Trade Commission sued the country's three largest pharmacy benefit managers on Friday, accusing them of steering diabetes patients towards higher priced insulin in order to reap millions of dollars in rebates from pharmaceutical companies.

Regulators say the nation's largest pharmacy benefit managers are partly to blame for the soaring cost of insulin in the U.S.

The three price benefit managers jointly administer 80% of all prescriptions in the U.S., the FTC said in the lawsuit.