Metformin

Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.

About Metformin

What it is

Metformin is the most widely used medicine for type 2 diabetes, of the biguanide group. It lowers blood sugar mainly by reducing how much glucose the liver releases, and it improves the body's response to insulin without causing low blood sugar on its own. It is also used for polycystic ovary syndrome. It is sold as Glucophage, among other names.

How genes come into it

Metformin is not broken down at all; it is moved into and out of cells by transporters, and those genes are the most studied. SLC22A1 (OCT1) carries it into the liver, and common reduced-function versions have been linked in some studies to a weaker effect and to stomach side effects; SLC47A1 and SLC47A2 (MATE1 and MATE2) and SLC22A2 move it into the urine. A genome-wide study also pointed to the ATM region. The results are mixed, and there is no CPIC or DPWG guideline.

What research found

Every published finding on gene variants and Metformin. Upload your DNA file to see which of these rows apply to you.

Rated evidence (30 rated variants)

PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.

SLC22A1 rs12208357: Level 3. Metabolism/PK. 5.

SLC47A1 rs2289669: Level 3. Efficacy: Diabetes Mellitus, Type 2, Polycystic Ovary Syndrome. 5.

SLC47A2 rs12943590: Level 3. Efficacy: Diabetes Mellitus. 4.

SLC47A2 rs12943590: Level 3. Metabolism/PK. 4.

Metabolism (25 findings)

Studies of how quickly the body processes this medication.

SLC22A1 rs12208357: Allele T is associated with increased exposure to metformin in healthy individuals as compared to allele C.

SLC22A1 rs12208357: Genotype TT is associated with decreased exposure to metformin in healthy individuals as compared to genotype CC.

SLC22A1 rs2282143: Genotype CC is associated with increased clearance of metformin in healthy individuals as compared to genotypes CT + TT.

SLC22A1 rs72552763: Genotype del/del is associated with decreased exposure to metformin in healthy individuals as compared to genotype GAT/GAT.

Response (88 findings)

Studies of how well it worked in people carrying a variant.

rs10783050: Genotype TT is associated with increased response to metformin in people with Diabetes Mellitus as compared to genotypes CC + CT.

rs6719578: Genotype CG is associated with increased response to metformin as compared to genotype GG.

ABCC8, KCNJ11 rs5219: Genotypes CT + TT is associated with increased clinical benefit to metformin and sulfonamides, urea derivatives in people with Diabetes Mellitus, Type 2 as compared to genotype CC.

ARFGEF3 rs143276236: Genotype AC is associated with decreased clinical benefit to metformin in people with Diabetes Mellitus, Type 2 as compared to genotype CC.

Study findings and evidence levels: PharmGKB (CC BY-SA 4.0). Guidelines: CPIC and DPWG, as bundled in PharmCAT. Most studies were done mainly in people of European ancestry.

Related Drugs

More drugs from the same category

Actos (Thiazolidinediones)

Amaryl (Sulfonylureas)

Antithyroid Drugs (class) (Antithyroid Agents)

Not a prescribing recommendation. This page is educational information about pharmacogenomic research and clinical guidelines - it is not medical or dosing advice, and not a prediction of how any medication will work for you. Never start, stop, or change a medication or dose based on it; talk to your doctor or pharmacist, who can order clinical-grade testing if appropriate.

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Content updated September 2026.

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