California Gov. Gavin Newsom has vetoed a bill that would have blocked insurance companies from charging more than $35 for a month's supply of insulin.

The bill would have banned health plans and disability insurance policies from imposing any out-of-pocket expenses on insulin prescription drugs above $35 for a 30-day supply. That would have included deductibles and co-pays.

Newsom, a Democrat, said earlier this year that California would soon start making its own brand of insulin. The state has a $50 million contract with the nonprofit pharmaceutical company Civica Rx to manufacture the insulin under the brand CalRx. The state would sell a 10-milliliter vial of insulin for $30.

"With CalRx, we are getting at the underlying cost, which is the true sustainable solution to high-cost pharmaceuticals," Newsom wrote in a message explaining why he vetoed the bill on Saturday. "With copay caps, however, the long-term costs are still passed down to consumers through higher premiums from health plans."

Insulin is a hormone produced by the pancreas that converts sugar into energy. People who have diabetes don't produce enough insulin. People with Type 1 diabetes must take insulin every day to survive.

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Bill's Sponsor, Scott Wiener, Says Veto Is 'Missed Opportunity'

State Sen. Scott Wiener, a Democrat from San Francisco who crafted the bill, called Newsom's veto "a major setback that will keep tens of thousands of diabetic Californians trapped in the terrible choice between buying insulin and buying food."

"This is a missed opportunity that will force them to wait months or years for relief from the skyrocketing costs of medical care when they could have had it immediately," Wiener said in a statement.

In January, California Attorney General Rob Bonta sued the companies that make and promote most of the nation's insulin, accusing them of colluding to illegally increase the price.

In March, the largest insulin makers announced they would voluntarily reduce the price of their products.