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

The US Federal Trade Commission said that CVS Health's Caremark, Cigna's Express Scripts, and UnitedHealth Group's Optum illegally steered patients to higher-priced insulins.

"Millions of Americans with diabetes need insulin to survive, yet for many of these vulnerable patients, their insulin drug costs have skyrocketed over the past decade thanks in part to powerful PBMs and their greed,