Metformin is the first-line drug for type 2 diabetes and one of the cheapest generic medications in the United States. A full 30-day supply costs $4 to $15 at retail pharmacies. Walmart, Costco, Kroger, and most other chains include metformin on their $4 generic lists.
Despite that low retail price, hospital inpatient bills routinely show metformin charges of $50 to $200 per single tablet. That is not a typo: hospitals bill oral medications at facility rates that bundle the drug acquisition cost with markup for nursing administration, storage, and pharmacy overhead. A 7-day hospital stay with two doses per day can put a $700 to $2,800 metformin charge on your bill for a drug that sells for $1 per tablet at retail. Many diabetic patients are also prescribed Januvia, Jardiance, or Farxiga alongside metformin — those drugs carry far higher costs and are worth comparing separately.
Metformin is an oral drug, so it is covered under Medicare Part D (prescription drug benefit) rather than Part B (provider-administered drugs). That means there is no Medicare J-code, no Part B ASP rate, and the price you pay at the pharmacy is set by your Part D plan formulary. Almost every Part D plan places metformin on Tier 1 (preferred generic) with a $0 to $5 monthly copay. Low-income patients who qualify for Medicaid pay $0 to $4 — check state Medicaid income limits.
What Metformin Costs by Point of Pay (2026)
The price you pay depends almost entirely on WHERE you pay. The same metformin can cost many times more at a hospital than at your local pharmacy:
2026 Metformin Price by Point of Pay| Where you pay | Typical cost | Notes |
|---|
| Pharmacy counter (retail) | $4 - $15 / 30-day supply | Walmart, Costco, Kroger $4 generic lists. GoodRx coupons often hit $4 to $9. |
| Inpatient hospital charge | $50 - $200 / tablet | Facility rate markup. Can total hundreds per day on an itemized bill. |
| Medicare Part D (plan-negotiated) | $0 - $5 / month copay | Tier 1 preferred generic on nearly every plan. No specific cap; falls under 2026 $2,100 Part D OOP cap. |
| Medicaid | $1 - $4 / prescription | All 50 states cover metformin as a preferred generic. |
Metformin has no Medicare Part B ASP rate because it is an oral drug billed under Part D. Retail prices reflect 2026 $4 generic programs at major pharmacy chains. Inpatient ranges reflect CMS Hospital Price Transparency data.
Source: CMS Hospital Price Transparency 2026, Medicare Part D formularies, Walmart $4 generic list
Why Hospitals Charge So Much
Hospitals bill oral medications at facility rates that bundle the drug acquisition cost with markup for nursing administration, pharmacy dispensing, storage, and overhead. Even for a generic that the hospital acquires for pennies per tablet, the facility rate can hit $50 to $200 per individual dose. That markup is legal under most state pricing rules, but it is also routinely disputed and reduced when patients ask for an itemized bill and challenge the line items.
Because metformin has no Medicare Part B ASP rate (it is a Part D drug), there is no single federal benchmark price hospitals must reference. However, you can still dispute inpatient charges by comparing them to the retail cash price ($4 to $15 per month), the Part D plan-negotiated rate ($0 to $5 per month), and any documented Medicaid reimbursement rate for your state. Charges that are 100x or more above retail are common targets for negotiation, especially if you are uninsured or have a high-deductible plan.
Patient Assistance Programs
Metformin is so cheap at retail that manufacturer patient assistance programs are usually unnecessary. The $4 generic programs at Walmart, Costco, Kroger, and other chains are the most practical route for uninsured patients. For extended-release brand-name versions (Glumetza, Fortamet) that can run $1,000+ per month, Bausch Health and Shire run brand-specific assistance programs.
Patient assistance programs for Metformin| Manufacturer program | Cost / Benefit | How to apply |
|---|
| Walmart $4 Generic Prescription Program | $4 for 30-day supply, $10 for 90-day supply | walmart.com/cp/4-prescriptions/1078664 |
| Costco Member Prescription Program | $4 to $9 per 30-day supply (no insurance required for cash price) | costco.com/pharmacy |
| GoodRx Discount Card | $4 to $9 per 30-day supply at participating pharmacies | goodrx.com/metformin |
| NeedyMeds Drug Discount Card | Free discount card, varies by pharmacy | needymeds.org |
Most patients will pay less with a $4 generic program than with manufacturer assistance for generic metformin. Brand-name extended-release versions are the exception.
Source: Walmart Pharmacy, GoodRx, NeedyMeds.org
Medicare Part D
Metformin is covered by every Medicare Part D plan, almost always on Tier 1 (preferred generic) with a $0 to $5 monthly copay. There is no specific federal cap for metformin like there is for insulin ($35/month under the IRA). Instead, your total annual out-of-pocket spending under Part D is capped at $2,100 in 2026, after which you pay $0 for all covered prescription drugs for the rest of the year. Because metformin is so cheap, you are unlikely to hit that cap from metformin alone, but it counts toward the cap alongside any other Part D drugs you take.
If your Part D plan is charging you more than $10 per month for generic metformin, switch plans during open enrollment (October 15 to December 7 each year) or appeal to the plan to move it to Tier 1. Use the Medicare Plan Finder at medicare.gov to compare plans by total cost.
Common Metformin Billing Errors
If you received a hospital bill showing $50 or more per metformin tablet, check for these errors before paying:
- Billed at the brand-name rate (Glumetza, Fortamet) when generic metformin was actually dispensed
- Wrong strength billed (1000 mg charge for a 500 mg tablet)
- Extended-release (ER) version billed when immediate-release was given
- Same dose billed twice (the same tablet logged twice on the medication administration record)
- Nursing administration fee added separately on top of an inflated drug charge
- Tablets charged for days when the patient was NPO (nothing by mouth) and did not actually receive the drug
Frequently Asked Questions
Why is metformin so cheap at the pharmacy but so expensive on a hospital bill?
Generic metformin retails for $4 to $15 for a 30-day supply because it has been off-patent for decades and is one of the most-prescribed generics in the United States. Hospital inpatient bills add facility-rate markup that bundles the drug acquisition cost with nursing administration, pharmacy dispensing, storage, and overhead. The result is $50 to $200 per individual tablet on an itemized bill. The cost difference is markup, not drug acquisition cost.
Does Medicare cover metformin?
Yes. Metformin is covered by every Medicare Part D plan, almost always on Tier 1 (preferred generic) with a $0 to $5 monthly copay. Metformin is not covered under Medicare Part B because it is an oral drug, not a provider-administered drug. There is no Medicare J-code and no Part B ASP rate for metformin. Your Part D plan negotiates the price directly with pharmacies.
What is the cheapest way to get metformin without insurance?
The Walmart $4 generic program offers a 30-day supply of generic metformin (500 mg or 1000 mg) for $4 or a 90-day supply for $10. Costco, Kroger, and other major chains have similar generic programs. GoodRx coupons also discount metformin to $4 to $9 per month at most pharmacies. No insurance is required for these cash prices.
Why does metformin have no J-code?
HCPCS J-codes are billing codes for drugs administered by a healthcare provider in a clinical setting, such as injections and infusions. Metformin is an oral tablet that patients take at home, so it is billed under Medicare Part D (the outpatient prescription drug benefit) rather than Part B. Part D drugs do not use J-codes; they are tracked by NDC (National Drug Code) at the pharmacy. The lack of a J-code is normal for oral medications.
Can I dispute an inpatient metformin bill?
Yes. If you received an itemized hospital bill showing $50 or more per metformin tablet, you can dispute the charge as excessive. Compare each line to the retail cash price ($4 to $15 per month, or about $0.15 per tablet) and the Part D plan-negotiated rate. Charges that are 100x or more above retail are common targets for negotiation. Ask for an itemized bill, check for duplicate doses or wrong-strength billing, and request a markdown to a reasonable rate.
Is generic metformin as effective as brand-name Glucophage?
Yes. Generic metformin is bioequivalent to brand-name Glucophage and is required by the FDA to deliver the same active ingredient at the same dose. Most diabetes specialists prescribe generic metformin. Brand-name extended-release versions like Glumetza and Fortamet use different release mechanisms and can cost $1,000 or more per month, but generic extended-release metformin is also available for under $30 per month at most pharmacies.
Will Medicaid cover metformin?
Yes. Medicaid covers metformin in all 50 states as a preferred generic with a typical copay of $1 to $4 per prescription. Some states have zero-dollar copays for generic diabetes medications. If you have low income and are not enrolled in Medicaid, you may qualify. Apply through your state Medicaid agency or healthcare.gov.
Does the Inflation Reduction Act cap metformin like it caps insulin?
No. The Inflation Reduction Act capped insulin out-of-pocket cost at $35 per month for Medicare Part D enrollees starting in 2023, but there is no similar specific cap for metformin. Metformin spending instead falls under the general 2026 Part D annual out-of-pocket cap of $2,100. Because metformin is so cheap, most patients pay $0 to $5 per month and never approach that cap from metformin alone.
