Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 4 complete abstracts (677 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
A biguanide hypoglycemic agent used in the treatment of non-insulin-dependent diabetes mellitus not responding to dietary modification. Metformin improves glycemic control by improving insulin sensitivity and decreasing intestinal absorption of glucose. (From Martindale, The Extra Pharmacopoeia, 30th ed, p289)
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Dimethylbiguanidine; Dimethylguanylguanidine; Glucophage; Metformin Hydrochloride; Hydrochloride, Metformin; Metformin HCl; HCl, Metformin.
Where it fits in the MeSH classification
- Broader topics
- Biguanides
- Narrower topics
- Sitagliptin Phosphate, Metformin Hydrochloride Drug Combination
Research landscape
PubMed indexes 21,482 records tagged with the MeSH heading “Metformin” (counts retrieved 2026-10-31). 8,038 of them (37.4%) were published from 2020 onward, and the busiest period so far is 2010-2019 with 9,361 records.
Reviews account for 3,427 records (16.0%) and meta-analyses for 789. Randomized controlled trials number 3,027 (14.1%) as a share of all records on the topic. Randomized trials make up a comparatively large share of this literature, which means many treatment questions have been tested directly.
Show the data
| Period | Records |
|---|---|
| through 1999 | 876 |
| 2000-2009 | 3,207 |
| 2010-2019 | 9,361 |
| 2020 onward | 8,038 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 3,427 | 16.0% |
| Meta-analyses | 789 | 3.7% |
| Randomized controlled trials | 3,027 | 14.1% |
Method: PubMed query "Metformin"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.
Reading the evidence in drugs and chemicals
Studies of a chemical or drug can answer very different questions: what it is and how it behaves in cells and animals, how the body handles it, and whether it changes outcomes in people. Laboratory and animal findings often do not carry over to patients, and observational studies of exposures are confounded by who uses a substance and why. Nothing on this page is a recommendation to use, avoid, start or stop any substance or medicine; talk to a qualified clinician or pharmacist about your own situation. Check the dose, the species, the comparison group and whether a patient-relevant outcome was measured.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| Neuroprotective Effects of Metformin Through the Modulation of Neuroinflammation and Oxidative Stress | 2025 | Review article Design not recorded in structured metadata | 38 | cc by PMID 40710317 · DOI · PMC12293675 |
| Systemic and gut microbiome changes with metformin and liraglutide in youth-onset type 2 diabetes: the MIGHTY study | 2025 | Randomized controlled trial Design not recorded in structured metadata | 21 | cc0 PMID 41020378 · DOI · PMC12482426 |
| Emerging uncertainty on the anti-aging potential of metformin | 2025 | Review article Design not recorded in structured metadata | 16 | cc by PMID 40582648 · DOI · PMC13329735 |
| Metformin inhibits mitochondrial complex I in intestinal epithelium to promote glycaemic control | 2026 | Research article Design not recorded in structured metadata | 11 | cc by PMID 42103929 · DOI · PMC13303093 |
Neuroprotective Effects of Metformin Through the Modulation of Neuroinflammation and Oxidative Stress [1]
Abstract reading summary — source excerpts
- Opening excerpt
- Epidemiological studies have shown that individuals with type 2 diabetes have an increased risk of developing neurodegenerative diseases.
- Closing excerpt
- Evidence from both clinical and preclinical studies indicates a complex and multifaceted impact, with benefits varying among populations and depending on underlying disease conditions, making it an appealing candidate for managing several neurodegenerative diseases.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (200 words)
Epidemiological studies have shown that individuals with type 2 diabetes have an increased risk of developing neurodegenerative diseases. These diseases and type 2 diabetes share several risk factors. Meanwhile, the antidiabetic drug metformin offers promising neuroprotective effects by reducing oxidative stress and neuroinflammation, two significant factors in neurodegenerative diseases. This review examines the mechanisms by which metformin mitigates neuronal damage. Metformin reduces neuroinflammation by inhibiting microglial activation and suppressing proinflammatory cytokines. It also triggers the nuclear factor erythroid-2-related factor-2 (Nrf2) pathway to combat oxidative stress, an essential regulator of antioxidant defenses. These outcomes support the possible neuroprotective roles of metformin in type 2 diabetes-related cognitive decline and conditions like Alzheimer's disease. Metformin's therapeutic potential is further supported by its capacity to strengthen the blood-brain barrier's (BBB's) integrity and increase autophagic flux. Metformin also offers several neuroprotective effects by targeting multiple pathological pathways. Moreover, metformin is being studied for its potential benefits beyond glycemic control, particularly in the areas of cognition, Alzheimer's disease, aging, and stroke management. Evidence from both clinical and preclinical studies indicates a complex and multifaceted impact, with benefits varying among populations and depending on underlying disease conditions, making it an appealing candidate for managing several neurodegenerative diseases.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 40710317 · DOI · PMC12293675
Systemic and gut microbiome changes with metformin and liraglutide in youth-onset type 2 diabetes: the MIGHTY study [2]
Abstract reading summary — source excerpts
- Opening excerpt
- Metformin (Met) and liraglutide (Lira) are preferred diabetes therapies that may improve glycemia by modulating the gut microbiome, but the mechanisms and pathways are unknown and few data exist in youth-onset type 2 diabetes (Y-T2D).
- Closing excerpt
- gov identifier: NCT02960659.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (143 words)
Metformin (Met) and liraglutide (Lira) are preferred diabetes therapies that may improve glycemia by modulating the gut microbiome, but the mechanisms and pathways are unknown and few data exist in youth-onset type 2 diabetes (Y-T2D). In a 3-month parallel clinical trial in African American Y-T2D randomized to Met (n = 14) or Met+Lira (n = 11), we compared gut microbial composition and metabolomic profiles and determined the relationship of changes in microbial abundance with glycemia and plasma metabolites. After 3 months, Met was associated with greater relative abundance of Eubacterium and Eubacterium rectale and lower Bacteroides ovates (p Bacteroides fragilis and lower Streptococcus thermophilus (p 1.5-fold) plasma cholic secondary bile acids (sulfochenodeoxycholic acid, nutriacholic acid, alpha-muricholic acid, and C24 dihydroxy bile acid; p ≤ 0.002). The change in nutriacholic acid correlated with lower fasting glucose (r = -0.7, p Clinical trials.gov identifier: NCT02960659.
Abstract reproduced from the open-access article under the recorded cc0 licence; © the authors. PMID 41020378 · DOI · PMC12482426
Emerging uncertainty on the anti-aging potential of metformin [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Metformin is the most commonly prescribed glucose-lowering agent worldwide for the treatment of type II diabetes.
- Closing excerpt
- These developments generally illustrate an emerging uncertainty in the anti-aging potential of metformin.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (176 words)
Metformin is the most commonly prescribed glucose-lowering agent worldwide for the treatment of type II diabetes. Due to evidence of improvements in healthspan and lifespan in model organisms, and mechanistic data relevant to the hallmarks of aging, it has been considered a promising candidate in the search for pharmacological interventions that may attenuate the ageing process in humans. Various epidemiological studies have been influential in generating support for this hypothesis. These include pronounced anticancer and cardioprotective benefits compared to other antidiabetic treatments, and an observation of metformin use in type II diabetes being associated with better survival than that of the general population. Here we discuss recent developments in the evidence underlying the rationale for using metformin to target ageing. We describe the methodological limitations of some of the early and most influential findings and critically assess their scientific follow-up, including replication attempts of key experimental and observational findings, and a range of clinical trials of metformin in individuals without type II diabetes. These developments generally illustrate an emerging uncertainty in the anti-aging potential of metformin.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 40582648 · DOI · PMC13329735
Metformin inhibits mitochondrial complex I in intestinal epithelium to promote glycaemic control [4]
Abstract reading summary — source excerpts
- Opening excerpt
- Metformin is a versatile biguanide drug primarily prescribed for type II diabetes.
- Closing excerpt
- Notably, the efficacy of phenformin, another biguanide, and berberine, a structurally unrelated nutraceutical, similarly depends on intestine-specific mitochondrial complex I inhibition, underscoring a shared therapeutic mechanism.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (158 words)
Metformin is a versatile biguanide drug primarily prescribed for type II diabetes. Despite its extensive use, the mechanisms underlying its clinical effects, including attenuated postprandial glucose excursions and elevated intestinal glucose uptake, remain unclear. Here we map these and other effects of metformin to intestine-specific mitochondrial complex I inhibition. Using human metabolomic data and an orthogonal genetics approach in male mice, we demonstrate that metformin suppresses citrulline synthesis, a metabolite generated exclusively by small intestine mitochondria, and increases GDF15 by inhibiting the mitochondrial respiratory chain at complex I. This inhibition co-opts the intestines to function as a glucose sink, driving the uptake of excess glucose and its conversion to lactate and lactoyl-phenylalanine. We also find that glucose lowering by metformin is due to repeated bolus exposure rather than a cumulative chronic response. Notably, the efficacy of phenformin, another biguanide, and berberine, a structurally unrelated nutraceutical, similarly depends on intestine-specific mitochondrial complex I inhibition, underscoring a shared therapeutic mechanism.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42103929 · DOI · PMC13303093
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Metformin and cancer risk in diabetic patients: a systematic review and meta-analysis [5]
- Research article Metformin as an adjuvant treatment for cancer: a systematic review and meta-analysis [6]
- Research article Metformin reduces all-cause mortality and diseases of ageing independent of its effect on diabetes control: A systematic review and meta-analysis [7]
- Research article Metformin and cancer risk and mortality: a systematic review and meta-analysis taking into account biases and confounders [8]
- Research article Glibenclamide, metformin, and insulin for the treatment of gestational diabetes: a systematic review and meta-analysis [9]
- Research article Metformin: Is it a drug for all reasons and diseases? [10]
References
- Reed S, Taka E, Darling-Reed S, Soliman KFA. Neuroprotective Effects of Metformin Through the Modulation of Neuroinflammation and Oxidative Stress. . 2025. PMID 40710317 · DOI · PMC12293675
- Glaros SB, Mishra SP, Jain S, Davis FS, Gabel SA, Mueller GA, et al.. Systemic and gut microbiome changes with metformin and liraglutide in youth-onset type 2 diabetes: the MIGHTY study. . 2025. PMID 41020378 · DOI · PMC12482426
- Keys MT, Hallas J, Miller RA, Suissa S, Christensen K. Emerging uncertainty on the anti-aging potential of metformin. . 2025. PMID 40582648 · DOI · PMC13329735
- Sebo ZL, Chakrabarty RP, Grant RA, D'Alessandro KB, Koss AR, Blum JLE, et al.. Metformin inhibits mitochondrial complex I in intestinal epithelium to promote glycaemic control. . 2026. PMID 42103929 · DOI · PMC13303093
- Decensi A, Puntoni M, Goodwin P, Cazzaniga M, Gennari A, Bonanni B, et al.. Metformin and cancer risk in diabetic patients: a systematic review and meta-analysis. Cancer Prev Res (Phila). 2010. PMID 20947488 · DOI
- Coyle C, Cafferty FH, Vale C, Langley RE. Metformin as an adjuvant treatment for cancer: a systematic review and meta-analysis. Ann Oncol. 2016. PMID 27681864 · DOI · PMC5178140
- Campbell JM, Bellman SM, Stephenson MD, Lisy K. Metformin reduces all-cause mortality and diseases of ageing independent of its effect on diabetes control: A systematic review and meta-analysis. Ageing Res Rev. 2017. PMID 28802803 · DOI
- Gandini S, Puntoni M, Heckman-Stoddard BM, Dunn BK, Ford L, DeCensi A, et al.. Metformin and cancer risk and mortality: a systematic review and meta-analysis taking into account biases and confounders. Cancer Prev Res (Phila). 2014. PMID 24985407 · DOI · PMC4154969
- Balsells M, García-Patterson A, Solà I, Roqué M, Gich I, Corcoy R. Glibenclamide, metformin, and insulin for the treatment of gestational diabetes: a systematic review and meta-analysis. BMJ. 2015. PMID 25609400 · DOI · PMC4301599
- Triggle CR, Mohammed I, Bshesh K, Marei I, Ye K, Ding H, et al.. Metformin: Is it a drug for all reasons and diseases?. Metabolism. 2022. PMID 35640743 · DOI
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-10-31.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.