Observational studyPloS one2018
The association of metformin use with vitamin B12 deficiency and peripheral neuropathy in Saudi individuals with type 2 diabetes mellitus.
Observational study in PloS one, 2018. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 43 papers, 2 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.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
43 citing papers in PubMed, 2 syntheses or guidelines pooled it, 90 citations in OpenAlex.
- Metformin for neurocognitive dysfunction in schizophrenia: a systematic review.Frontiers in psychiatry · 2024Pooled it
- Adjunctive metformin for antipsychotic-induced dyslipidemia: a meta-analysis of randomized, double-blind, placebo-controlled trials.Translational psychiatry · 2020Pooled it
- A randomized clinical trial assessing the efficacy of vitamin B prophylaxis in attenuating paclitaxel-induced neuropathy and the imperative use of gabapentin in diabetic ovarian cancer patients.Medical oncology (Northwood, London, England) · 2026Trial
- Vitamin B12 Supplementation in Diabetic Neuropathy: A 1-Year, Randomized, Double-Blind, Placebo-Controlled Trial.Nutrients · 2021Trial
- Repurposing metformin for choriocarcinoma: targeting the AMPK/mTOR pathway.Naunyn-Schmiedeberg's archives of pharmacology · 2026Review
- Empowering community pharmacists: expert consensus guidance for the effective management of peripheral neuropathy with neurotropic B vitamins.Journal of pharmaceutical health care and sciences · 2026Article
- Metformin-induced vitamin B12 deficiency: An underdiagnosed cause of diabetic neuropathy.World journal of diabetes · 2025Review
- Vitamin B12 Deficiency in Patients With Diabetic Peripheral Neuropathy: A Hospital-Based Cross-Sectional Study.Cureus · 2025Article
- Dose dependent relationship of metformin use and diabetic peripheral neuropathy risk in patients with type 2 diabetes mellitus.Scientific reports · 2025Article
- Dose-Dependent Relationship Between Long-Term Metformin Use and the Risk of Diabetic Retinopathy: A Population-Based Cohort Study.Clinical drug investigation · 2025Article
- Current Perspectives in Pre- and Diabetic Peripheral Neuropathy Diagnosis and Management: An Expert Statement for the Gulf Region.Diabetes therapy : research, treatment and education of diabetes and related disorders · 2024Review
- Metformin Use and Vitamin B12 Deficiency in People with Type 2 Diabetes. What Are the Risk Factors? A Mini-systematic Review.TouchREVIEWS in endocrinology · 2024Review
- Review
- Vitamin BIrish journal of medical science · 2024Review
- Metformin-Induced Vitamin B12 Deficiency in Patients with Type 2 Diabetes: A Narrative Review with a Practical Approach for Screening, Diagnosing, and Managing Vitamin B12 Deficiency.Korean journal of family medicine · 2024Article
- Evaluating Physician Knowledge, Attitudes, and Practices in Screening and Supplementation for Vitamin B12 Deficiency in Type 2 Diabetes Patients Treated with Metformin.Diabetes, metabolic syndrome and obesity : targets and therapy · 2024Article
- Micronutrient status in patients with diabetic foot ulcers: A cross-sectional study in Saudi Arabia.Journal of family medicine and primary care · 2024Article
- The correlation between vitamin B12 and folate levels and bone mineral density among the Saudi population in a primary care setting.Journal of family medicine and primary care · 2023Article
- The Correlation between Metformin Use and Incident Dementia in Patients with New-Onset Diabetes Mellitus: A Population-Based Study.Journal of personalized medicine · 2023Article
- [Diabetic neuropathy and diabetic foot syndrome (update 2023)].Wiener klinische Wochenschrift · 2023Article
Corrections and comments
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Authors and funding
10 authors at 1 institution in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
aimsTo compare the prevalence of vitamin B12 deficiency and peripheral neuropathy between two groups of type 2 diabetes mellitus (T2DM) patients treated with or without metformin, and to determine factors associated with vitamin B12 deficiency therapy and dietary intake of vitamin B12.
methodsIn this retrospective study, we recruited 412 individuals with T2DM: 319 taking metformin, and 93 non-metformin users. Demographics, dietary assessment for vitamin B12 intakes, and medical history were collected. Participants were assessed for peripheral neuropathy. Blood specimens were collected and checked for serum vitamin B12 levels. The differences between the two groups were analyzed using an independent t-test for continuous data, and the Chi-squared or Fisher's exact test was used for categorical data. The relationship of vitamin B12 deficiency with demographics and clinical characteristics was modeled using logistic regression.
resultsThe prevalence of B12 deficiency was 7.8% overall, but 9.4% and 2.2% in metformin users and non-metformin users, respectively. The odds ratio for serum vitamin B12 deficiency in metformin users was 4.72 (95% CI, 1.11-20.15, P = 0.036). There were no significant differences in a test of peripheral neuropathy between the metformin users and non-metformin users (P > 0.05). Low levels of vitamin B12 occurred when metformin was taken at a dose of more than 2,000 mg/day (AOR, 21.67; 95% CI, 2.87-163.47) or for more than 4 years (AOR, 6.35; 95% CI, 1.47-24.47).
conclusionIndividuals with T2DM treated with metformin, particularly those who use metformin at large dosages (> 2,000 mg/day) and for a longer duration (> 4 years), should be regularly screened for vitamin B12 deficiency and metformin is associated with B12 deficiency, but this is not associated with peripheral neuropathy.
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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.