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Janumet is a brand of metformin / sitagliptin. What agents check before quoting it: how many 2026 Part D plans cover it, on which tier, with what restrictions and copays, by plan type, carrier and state.
In 2026, 5,232 of 5,496 Medicare Part D and Medicare Advantage drug plans (95.2%) list Janumet on their formulary, across 316 of 328 formularies. The most common placement is tier 3 (4,993 plans, 95.4% of those covering it). 7 of the covering plans require prior authorization (0.1%), 0 step therapy and 5,113 a quantity limit.
1,531 covering plans charge a flat copay for a 30-day supply at a preferred retail pharmacy after the deductible — median $47, 128 of them $0; 3,701 charge coinsurance instead — median 24% of the drug's cost. Once a member's out-of-pocket drug spending reaches $2,100 in 2026, covered drugs cost $0 for the rest of the year.
Janumet has a Medicare negotiated price (maximum fair price) of $80 for a 30-day supply, which takes effect in 2027. The negotiated price lowers what the plan pays; the member's copay or coinsurance still follows the plan's tier.
2025: 5,465 of 5,631 plans covered it (97.1%); 2026: 5,232 of 5,496 (95.2%).
Of 4,368 plans offered in both years, 26 added it to the formulary and 99 dropped it.
Among plans covering it both years, 276 moved it to a higher tier and 15 to a lower one; 5 added prior authorization and 0 removed it.
Medicare Part D paid for 2,159,527 30-day fills of Janumet in 2024 for about 245,168 enrollees, at an average total cost of $492.90 per 30-day fill (CMS Part D Prescribers by Geography and Drug, national).
Price Janumet and the rest of a client's list on every plan in their county.
Estimate Janumet costs by plan
Free tools for licensed insurance agents. Data from CMS public files; verify with plan documents before advising a client.
Counts are over every Medicare Advantage drug plan and stand-alone Part D plan in the CMS monthly formulary files, excluding employer plans. A plan counts as covering a drug when any strength or form of it is on the plan’s formulary; the tier, prior authorization, step therapy and quantity limit shown are the most favorable version on that formulary. Copays are for a 30-day supply at a preferred retail pharmacy after the deductible. This is a reference for licensed agents, not a plan recommendation; verify with the plan’s formulary before advising a client. Source: CMS Part D formulary files (release 09/16/2026). CMS formulary data.