Narrative reviewindependent cross-checkabstract checked I-ODD-115 standard review
Metformin and low B12 also seen in Arab countries
Vitamin B12 Deficiency in Patients with Diabetes on Metformin: Arab Countries.
Overview
Alhaji JH. Nutrients 2022 · PMID 35631186 · DOI 10.3390/nu14102046
11 regional studies point to more B12 deficiency with longer and higher-dose metformin use.
Does the study support the specific claim? Yes · Methodological quality: low
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Review Arab-region studies.
- How was the study done?
Literature review.
- How many people, animals or samples were studied?
11 studies.
- What was actually found?
Association with dose and duration.
- How large was the observed effect?
Not pooled.
- What do the results mean in everyday life?
The same monitoring advice applies in the region.
- What are the study's limitations?
Narrative, single author.
- What does it say about Elawady's specific claim?
Supports it regionally.
- Do the results apply to Germany and Europe?
Not applicable.
- What can explicitly not be concluded from this study?
Size of the effect in Egypt.
Scientific in-depth review
1. Full reference
- Authors
- Alhaji JH
- Journal
- Nutrients
- Year
- 2022
- Identifier
- PMID 35631186 DOI 10.3390/nu14102046
- Verification
- verified – PubMed efetch 2026-10-26; Crossref works API 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
Not stated in abstract.
2. Research question
Is metformin associated with B12 deficiency in patients with type 2 diabetes in Arab countries?
3. Study design and population
- Study design
- Narrative review – Narrative/systematic literature review of studies from Arab countries
- Population
Patients with type 2 diabetes in Arab/Middle Eastern countries
- Country
Arab countries (Saudi Arabia, Qatar and others)
- Period
Published before 2020
- Sample size
11 studies
- Inclusion and exclusion criteria
English-language studies in PubMed and Web of Knowledge
4. Methods and endpoints
- Exposure / intervention
Metformin
- Comparator
Non-users or lower dose/duration
- Endpoints
B12 deficiency, neuropathy, physician knowledge
- Statistical methods
Narrative
5. Actual results
- Results
11 studies indicated an association between metformin and B12 deficiency in Arab countries, related to dose and duration of therapy; physician knowledge of ADA recommendations influenced screening.
- Absolute risks
Not reported.
- Authors' conclusion
Metformin is associated with B12 deficiency in Arab countries; B12 should be routinely monitored in long-term users.
6. Strengths
- Regional evidence
7. Weaknesses
- Single author
- No meta-analysis
- One included Qatari study found no association (29887831, not reviewed in detail)
8. Risk of bias
- Orienting tool
- none applicable
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Narrative synthesis.
9. Assessment of the statistical interpretation
No pooled estimate.
10. Relevance to the specific claim
Shows the B12 effect is also documented in the Arab region (relevant to Egyptian readers); no Egypt-specific study found.
11. Independent contrary findings
A Qatari study (PMID 29887831; not reviewed in detail) reported no association.
12. Transferability to Germany and Europe
Not applicable; regional relevance for Egypt.
13. Overall methodological judgement
Regional confirmation, low methodological weight.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | low |
| Risk of bias | some concerns |
| Precision of results | not applicable |
| Directness | direct |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | mixed |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Egyptian data.