No, supplemental Medicare insurance (sometimes referred to as Medigap) is not the same as Medicare Premiums.
Medigap plans limit Medicare enrollees’ out-of-pocket exposure, covering some or all of an enrollee’s copay, coinsurance, and deductibles (benefits vary by plan).
Some Medigap plans also cover a portion of emergency medical expenses incurred during travel outside the United States and its territories.
Medigap plans are sold by private insurance companies (for example Blue Cross Blue Shield) that agree to abide by federal Medicare guidelines.