From AARP's website for this plan through them:
"You must meet the minimum age requirement of 65+ to be eligible. If you are not yet age 65, but eligible for Medicare by reason of disability, please call 1-866-270-8022 for more information."
Their Part D program covers anybody getting Medicare, they might offer similar insurance supplementation.
Also, are you possibly dual-eligible by income and assets? States run Medicare Savings Plans for low-income recipients. They are funded from Medicaid funds, but are not Medicaid. They are a form of Medical Assistance that covers premiums, deductables and co-pays.
Medicare Savings Program (MSP) Contact Information Click your state for the particulars to see if you are eligible. Most medical professional accepting Medicare accept MSP plans as well.