Metformin is the most widely prescribed diabetes medication and one of the most affordable prescription drugs available. As a generic medication on Tier 1 of virtually every formulary, metformin is covered with the lowest possible copay by all insurance types. Many plans and pharmacies offer metformin at $0 to $4 per month.

Key Facts

Metformin is on Tier 1 (preferred generic) of virtually every insurance formulary
Typical copay: $0 to $10 per month with insurance
Many retail pharmacies offer metformin for $4 per month without insurance (Walmart, Costco, etc.)
No prior authorization required on any major formulary
Available as immediate-release and extended-release (ER) tablets; both are generic and affordable
Metformin ER had an FDA recall in 2020 for NDMA contamination; reformulated versions are now available

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ACA marketplace enrollment runs November 1 to January 15. Medicare Annual Enrollment is October 15 to December 7. Compare formularies for your medications before choosing a plan.

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Coverage varies by plan. Use our formulary checker tool to look up your exact copay and restrictions.

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Frequently Asked Questions

Is metformin free with insurance?

Many insurance plans offer metformin at $0 copay, especially on ACA marketplace plans that cover certain preventive diabetes medications at no cost. Even plans with a copay rarely charge more than $5 to $10. Some pharmacy discount programs offer metformin for $4/month without insurance.

Do I need insurance to afford metformin?

No. Metformin is one of the most affordable prescription drugs available. Walmart, Costco, and many other pharmacies sell generic metformin for $4 per 30-day supply without insurance. GoodRx and other discount card programs often bring the price below $10. Insurance is helpful but not necessary for metformin affordability.

Is metformin ER covered differently than regular metformin?

Both immediate-release (IR) and extended-release (ER) metformin are generic and covered on Tier 1 by most plans. ER versions may be slightly more expensive but are still very affordable. Some brand-name ER formulations (like Glumetza) are much more expensive and may be on higher tiers.

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