Affordable Insulin for All Act This bill addresses insulin affordability. For example, the bill requires the Department of Health and Human Services (HHS) to enter into agreements with insulin manufacturers to enable individuals with diagnosed diabetes to access Medicaid prices for insulin drugs. Additionally, Medicare and private insurance plans must cap cost-sharing at $10 per month for insulin drugs, and HHS must revise regulations to exclude payments made for insulin drugs from the denominator of the medical loss ratio. The bill also (1) eliminates a safe harbor for certain rebates, discounts, or price concessions for insulin drugs paid by a drug manufacturer to a pharmacy benefit manager for purposes of federal health care fraud and abuse laws; and (2) prohibits certain drug pricing activities related to supplemental rebates and spread pricing in Medicaid. The Government Accountability Office must report on the feasibility and affordability of direct manufacturing by the federal government.