Insulin list prices have escalated dramatically during the past 5-10 years. This is due to only three manufacturers controlling the market, the lack of alternative insulins, and manufacturer abuse of patent extensions. PBMs drive competition using drug formularies and rebates. In spite of dramatic increases in list prices with total gross sales increasing from $22b in 2012 to $54b in 2019, net costs have been flat with total net sales of $13b in 2012 and remained the same $13b in 2019 due to PBM-negotiated rebates, statutory rebates, and other manufacturer discounts.