Insulin Price Reduction Act This bill prohibits health insurance plan issuers and pharmacy benefits managers (PBMs) from receiving rebates or discounts for insulin from manufacturers who certify that its current insulin list price has been reduced to an amount no greater than what the list price was for the same insulin on July 1, 2006. This restriction does not apply to discounts provided to insurance plan holders at retail sale or to flat-rate fees for service paid to PBMs. Further, insurance plans are prohibited from applying a deductible to insulin that has received such price certification. A manufacturer may certify insulin prices by submitting to the Department of Health and Human Services data about the list price of any insulin the manufacturer has produced since January 1, 2000, and by setting the current list price for an insulin product at the 2006 rate. To remain certified, a manufacturer may not increase the list price of insulin by more than the annual increase in the medical care consumer price index. A manufacturer may certify the price of an insulin product for which it did not have a list price in 2006 by reducing the list price of such insulin to the weighted average list price in 2006 of specified insulin categories. This bill also applies to Medicare prescription drug benefits. The bill sets the rebate for insulin under Medicaid based on the average manufacturer price of insulin during the last fiscal quarter of 2019, increasing by the medical care consumer price index thereafter.