Several months ago, Eli Lilly (LLY) launched a new version of its Humalog insulin at half of the list price, a move the company claimed would help lower costs for people with diabetes and blunt criticism of its pricing. But a new survey by a pair of lawmakers finds the new version is often out of stock at pharmacies, many of which were unaware the product was available.

The findings prompted renewed criticism of the drug maker for failing to take steps to ensure its strategy would lower costs for consumers. Although prescription drug prices are a hot-button issue across the U.S., the cost of insulin has been a flashpoint amid mounting reports of people driving to Canada to purchase the medicine or others who engage in rationing, sometimes leading to death.