U.S. drugmaker Eli Lilly and Co. announced plans on Monday to sell a half-price version of its popular insulin injection Humalog, as it fends off criticism about rising drug prices.

Major drugmakers including Lilly, a leading producer of insulin, have come under fire from patients and lawmakers over the rising cost of the life-saving medication used to treat diabetes.

Lilly's generic insulin product would be called Insulin Lispro, it said, while Humalog, one of the company's top-selling products with $3 billion in annual sales, will remain available for those wishing to access it through their existing insurance plans.

The move comes as the U.S. government increases scrutiny into the pharmaceutical industry and rising costs of prescription drugs in the United States, a top voter concern.

The cost of insulin for treating type 1 diabetes in the United States has nearly doubled over a five-year period, Reuters reported in January.

The list price for one vial of Insulin Lispro, which will be sold only in the United States, would be $137.35, Lilly said.

For uninsured patients or those with high-deductible insurance plans, Insulin Lispro can make insulin more affordable, the Indianapolis-based drugmaker added.

Lilly said it had spoken to various "stakeholders" about the price of insulin, including diabetes patients, doctors, advocacy groups, wholesalers and lawmakers.

"For people with diabetes, a lower-priced insulin can serve as a bridge that addresses gaps in the system until a more sustainable model is achieved," Lilly Chief Executive Officer David Ricks said in a statement.

Two U.S. senators last month launched an investigation into rising insulin prices, writing to Lilly and two other leading manufacturers, asking them why the cost of the nearly 100-year-old medication had rapidly risen.

The price of Humalog, for instance, rose from $35 to $234 per dose between 2001 and 2015, a 585 percent increase, the senators said.

Lilly has in the past called insulin a highly-rebated product.

Drugmakers often argue they have to keep prices high because of the rebates they must pay to pharmacy benefit managers and health insurers to get products on their lists of covered drugs.

The U.S. government in January proposed a rule to end the industry-wide system of rebates. Lilly has previously voiced its support for the proposal and on Monday it affirmed that stance.

"The significant rebates we pay on insulins do not directly benefit all patients," Ricks said. "This needs to change."