AARP Medicare Part D prescription drug plans are insured by UnitedHealthcare. More than 4 million Medicare beneficiaries have AARP/UnitedHealthcare Part D plans as of April 2022. Medicare Part D plans from AARP/UnitedHealthcare are widely available and get solid ratings for quality from the Centers for Medicare & Medicaid Services. Pricing for the highest-coverage option can... Alex Rosenberg writes for NerdWallet.