Trial reportDiabetologia2019
Metformin-induced changes of the gut microbiota in healthy young men: results of a non-blinded, one-armed intervention study.
Trial report in Diabetologia, 2019. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT02546050 (Effects of Metformin on Human Gut Microbiota), which is not on this map. Cited by 120 papers, 3 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Effects of Metformin on Human Gut Microbiota
Who cites it
120 citing papers in PubMed, 3 syntheses or guidelines pooled it, 196 citations in OpenAlex.
- Gastrointestinal adverse events of metformin treatment in patients with type 2 diabetes mellitus: A systematic review, meta-analysis and meta-regression of randomized controlled trials.Frontiers in endocrinology · 2022Pooled it
- Fecal microbiota transplantation treatment of autoimmune-mediated type 1 diabetes: A systematic review.Frontiers in cellular and infection microbiology · 2022Pooled it
- Effects of Non-insulin Anti-hyperglycemic Agents on Gut Microbiota: A Systematic Review on Human and Animal Studies.Frontiers in endocrinology · 2020Pooled it
- Systemic and gut microbiome changes with metformin and liraglutide in youth-onset type 2 diabetes: the MIGHTY study.Gut microbes · 2025Trial
- Glucocorticoid-induced changes of the gut microbiota and metabolic markers in healthy young men: Outcome of a randomized controlled trial.Cell reports. Medicine · 2025Trial
- Combining a diet rich in fermentable carbohydrates with metformin improves glycaemic control and reshapes the gut microbiota in people with prediabetes.Nature metabolism · 2025Trial
- Overall Structural Alteration of Gut Microbiota and Relationships with Risk Factors in Patients with Metabolic Syndrome Treated with Inulin Alone and with Other Agents: An Open-Label Pilot Study.Mediators of inflammation · 2022Trial
- Effects of vancomycin-induced gut microbiome alteration on the pharmacodynamics of metformin in healthy male subjects.Clinical and translational science · 2021Trial
- Metformin Affects Gut Microbiome Composition and Function and Circulating Short-Chain Fatty Acids: A Randomized Trial.Diabetes care · 2021Trial
- Lifestyle modifications result in alterations in the gut microbiota in obese children.BMC microbiology · 2021Trial
- Maternal Metformin Exposure Induces Gut Microbial Shifts in Non-Diabetic Dams and Sex-Stratified Changes in Mouse Offspring.Biomolecules · 2026Article
- Review
- The eternal struggle between titans: Fecal microbiota transplant (FMT) versus metformin in type 2 diabetes (T2D) gut dysmotility.Journal of advanced research · 2026Review
- Metformin in skin diseases: the role of gut microbiota and immune response.Pharmacological reports : PR · 2026Review
- Mechanistic Links Between the Gut Microbiome and Longevity Therapeutics.Biomedicines · 2026Review
- Metformin and Myo-Inositol: A Comparative Analysis.Gynecologic and obstetric investigation · 2026Review
- The interplay of dietary sugar, chronic inflammation, and bladder cancer: mechanistic insights, evidence, and prevention strategies.Frontiers in immunology · 2026Review
- Metformin-Associated Gastrointestinal Intolerance: A Narrative Review of Mechanisms and Clinical Management.Clinical medicine insights. Endocrinology and diabetes · 2026Review
- The Role of the Gut Microbiome Dysbiosis in Metabolic Dysfunction: A Mini Review.Healthcare (Basel, Switzerland) · 2025Review
- Impact of a Lifestyle Intervention on Gut Microbiome Composition: A Quasi-Controlled Before-and-After Analysis.Metabolites · 2025Article
60 more citing papers are in PubMed but not listed here.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
11 authors at 2 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
aims/hypothesisIndividuals with type 2 diabetes have an altered bacterial composition of their gut microbiota compared with non-diabetic individuals. However, these alterations may be confounded by medication, notably the blood-glucose-lowering biguanide, metformin. We undertook a clinical trial in healthy and previously drug-free men with the primary aim of investigating metformin-induced compositional changes in the non-diabetic state. A secondary aim was to examine whether the pre-treatment gut microbiota was related to gastrointestinal adverse effects during metformin treatment.
methodsTwenty-seven healthy young Danish men were included in an 18-week one-armed crossover trial consisting of a pre-intervention period, an intervention period and a post-intervention period, each period lasting 6 weeks. Inclusion criteria were men of age 18-35 years, BMI between 18.5 kg/m
resultsData from participants who completed visit 1 (n=23) are included in analyses. For the primary outcome the relative abundance of 11 bacterial genera significantly changed during the intervention but returned to baseline levels after treatment cessation. In line with previous reports, we observed a reduced abundance of Intestinibacter spp. and Clostridium spp., as well as an increased abundance of Escherichia/Shigella spp. and Bilophila wadsworthia. The relative abundance at baseline of 12 bacterial genera predicted self-reported gastrointestinal adverse effects. CONCLUSIONS/
interpretationIntake of metformin changes the gut microbiota composition in normoglycaemic young men. The microbiota changes induced by metformin extend and validate previous reports in individuals with type 2 diabetes. Secondary analyses suggest that pre-treatment gut microbiota composition may be a determinant for development of gastrointestinal adverse effects following metformin intake. These results require further investigation and replication in larger prospective studies.
trial registrationClinicaltrialsregister.eu 2015-000199-86 and ClinicalTrials.gov NCT02546050
fundingThis project was funded by Danish Diabetes Association and The Novo Nordisk Foundation.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.