Medicare Supplement Insurance (Medigap) plans are not HMO or PPO plans. Medicare Supplement Insurance plans are secondary to Medicare, who’s primary and pays your claims first typically. The Medicare Supplement Insurance plan can also pick up your deductibles and coinsurance that Medicare doesn’t pay. There are various standardized plans available. These plans are guaranteed renewable, which means the insurance company can’t cancel your Medigap policy as long as you pay the premium. Unlike the Medicare Advantage plans, which can change from year to year and can even go away. These plans do not cover the medication you pick up at the pharmacy, so you may need to add a Part D drug plan also.