SynthesisBMJ open diabetes research & care2020
Association between metformin and neurodegenerative diseases of observational studies: systematic review and meta-analysis.
Synthesis in BMJ open diabetes research & care, 2020. The graph read 2 numbers from its abstract, feeding 2 cells of the map, but none could be read as for or against, so it casts no vote. Cited by 53 papers, 4 of them syntheses that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
Read, but not usablea number the graph found but could not read as for or against
Meta-analysis found there was no significant effect on incidence of all the subtypes of NDs with metformin exposure (OR 1.04, 95% CI 0.92 to 1.17).
However, metformin monotherapy was associated with a significantly increased risk of PD incidence compared with non-metformin users or glitazone users (OR 1.66, 95% CI 1.14 to 2.42).
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Where it lands on the map
Rows are treatments, columns are outcomes. The coloured squares are the cells this paper feeds, coloured by the vote it casts there. Click one to jump to what this paper adds to it.
What it adds to each cell
For every cell the paper feeds: the belief in the claim with and without this paper, and this paper's estimate drawn against every other readable study in the cell. The ringed dot is this paper.
Metformin×pharmacokinetics & dosing
No readable resultOpen on the map →What to test next →2 readable studies in this cell: 0 favour the treatment, 2 find no difference, 0 favour the comparator.
This paper's own estimate is on a different scale from the rest of the cell, so it is not drawn here.
Thiazolidinediones×pharmacokinetics & dosing
No readable resultOpen on the map →What to test next →No other readable study in this cell yet. This paper is the evidence.
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.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
53 citing papers in PubMed, 4 syntheses or guidelines pooled it.
- Metformin and Cognitive Performance in Patients With Type 2 Diabetes: An Umbrella Review.Neuropsychopharmacology reports · 2025Pooled it
- Systematic review and meta-analysis of current guidelines, and their evidence base, on risk of renal function after administration of contrast medium for diabetic patients receiving metformin.Frontiers in medicine · 2025Pooled it
- Association between metformin use and the risk of developing open-angle glaucoma among patients with diabetes: a retrospective cohort study and meta-analysis.International ophthalmology · 2024 · on this mapPooled it
- Association Between Diabetes Medications and the Risk of Parkinson's Disease: A Systematic Review and Meta-Analysis.Frontiers in neurology · 2021Pooled it
- Metformin versus DPP-4 inhibitors and risk of parkinsonism in type 2 diabetes: an active-comparator cohort study with a landmark design.Diabetology & metabolic syndrome · 2026Article
- Metabolic reprogramming is critical to microglial activation in Huntington's disease.JCI insight · 2026Article
- Liraglutide attenuates aluminum chloride-induced Alzheimer's disease in rats by modulating the oxLDL/LPA/LPAR1 pathway.Communications biology · 2026Article
- Metformin for Longevity and Sarcopenia: A Therapeutic Paradox in Aging.Biomedicines · 2026Article
- SGLT2 inhibitors vs. metformin for Parkinson's disease risk reduction in type 2 diabetes.Journal of Parkinson's disease · 2025 · on this mapObservational
- Human Glucose Transporters in Health and Selected Neurodegenerative Diseases.International journal of molecular sciences · 2025Review
- Association of Metformin with the Risk of Dementia: A Population-Based Retrospective Cohort Study in Taiwan.Healthcare (Basel, Switzerland) · 2025Article
- Neuroprotective efficacy of berberine and caffeine against rotenone-induced neuroinflammatory and oxidative disturbances associated with Parkinson's disease via inhibiting α-synuclein aggregation and boosting dopamine release.Inflammopharmacology · 2025Article
- Overview of Metformin and Neurodegeneration: A Comprehensive Review.Pharmaceuticals (Basel, Switzerland) · 2025Review
- Metformin's Effects on Cognitive Function from a Biovariance Perspective: A Narrative Review.International journal of molecular sciences · 2025Review
- Targeting Ferroptosis in Parkinson's: Repurposing Diabetes Drugs as a Promising Treatment.International journal of molecular sciences · 2025Review
- Associations Between Diabetes Mellitus and Neurodegenerative Diseases.International journal of molecular sciences · 2025Review
- Exploring Novel Therapeutic Avenues: Drug Repurposing for Neurodegenerative Movement Disorders.Current drug research reviews · 2025Review
- Parkinson's disease and metabolic disorders, understanding their shared co-morbidity through the autonomic nervous system.Advances in genetics · 2025Review
- Exceeding the Limits with Nutraceuticals: Looking Towards Parkinson's Disease and Frailty.International journal of molecular sciences · 2024Review
- Metabolic Dysfunction in Parkinson's Disease: Unraveling the Glucose-Lipid Connection.Biomedicines · 2024Review
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
3 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
The marked sentences are the ones the graph read a number from.
BACKGROUND AND
aimsAging becomes a growing global concern with an increased risk of neurodegenerative diseases (NDs) that mainly consist of cognitive decline and Parkinson disease (PD). As the most commonly prescribed antidiabetic drug, metformin has been shown to have inconsistent roles in the incidence of NDs. We performed a systematic review and meta-analysis of observational studies to evaluate the effect of metformin exposure on onset of NDs.
methodsThe observational studies that investigated the associations between metformin and the incidence of NDs were searched in MEDLINE, Embase and Cochrane Library databases. A random-effect model was performed using STATA to calculate the combined ORs.
resultsIn total, 23 comparisons out of 19 studies with 285 966 participants were included. Meta-analysis found there was no significant effect on incidence of all the subtypes of NDs with metformin exposure (OR 1.04, 95% CI 0.92 to 1.17). However, metformin monotherapy was associated with a significantly increased risk of PD incidence compared with non-metformin users or glitazone users (OR 1.66, 95% CI 1.14 to 2.42).
conclusionMetformin has failed to demonstrate a beneficial effect on NDs. In addition, it may increase the risk of PD development. In light of current results, how metformin would impact NDs, especially the potential risk of PD, needs to be scrutinized. The underlying mechanisms are vital to achieve some more profound understanding on the regimen. TRIAL REGISTRATION NUMBER: CRD 42019133285.
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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 Socratic graph.