Otherindependent cross-checkabstract checked★ key study I-INS-121 in-depth review
Genes for higher insulin levels and heart disease
Exploring the pathways linking fasting insulin to coronary artery disease: a proteome-wide Mendelian randomization study.
Overview
Huang X et al.. BMC Med 2025 · PMID 40442727 · DOI 10.1186/s12916-025-04127-6
People genetically inclined to higher fasting insulin had a higher risk of coronary artery disease.
Does the study support the specific claim? Partly · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Test whether higher fasting insulin causes coronary disease.
- How was the study done?
Mendelian randomisation.
- How many people, animals or samples were studied?
Large genetic datasets.
- What was actually found?
OR 1.79 for CAD.
- How large was the observed effect?
OR 1.79 (1.34-2.40).
- What do the results mean in everyday life?
Insulin resistance with high natural insulin is bad for arteries.
- What are the study's limitations?
Instruments reflect insulin resistance; no data on insulin therapy.
- What does it say about Elawady's specific claim?
Supports the kernel about natural high insulin, not about insulin injections.
- Do the results apply to Germany and Europe?
Mostly European data.
- What can explicitly not be concluded from this study?
Cannot say insulin treatment causes atherosclerosis.
Scientific in-depth review
1. Full reference
- Authors
- Huang X et al.
- Journal
- BMC Med
- Year
- 2025
- Identifier
- PMID 40442727 DOI 10.1186/s12916-025-04127-6
- Verification
- verified – PubMed efetch 2026-10-26; Crossref 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
No competing interests (record).
2. Research question
Is genetically predicted fasting insulin causally associated with coronary artery disease, and through which proteins?
3. Study design and population
- Study design
- Other – Two-sample and proteome-wide Mendelian randomisation (MAGIC, CARDIoGRAMplusC4D, UKB-PPP, deCODE, FinnGen)
- Population
GWAS summary data (mostly European ancestry)
- Country
International consortia
- Period
Not applicable
- Sample size
GWAS summary statistics
- Inclusion and exclusion criteria
Genetic instruments for fasting insulin
4. Methods and endpoints
- Exposure / intervention
Genetically predicted endogenous fasting insulin
- Comparator
Per genetic unit
- Endpoints
Coronary artery disease
- Statistical methods
MR with sensitivity analyses and mediation
5. Actual results
- Results
Genetically predicted insulin associated with higher CAD risk, OR 1.79 (95% CI 1.34-2.40); 5 mediating proteins (PLA2G7, GZMA, LDLR, AGRP, HHEX), e.g. AGRP explaining 29.66% of the effect.
- Absolute risks
not reported
- Authors' conclusion
Five protein mediators link insulin to CAD.
6. Strengths
- Genetic design reduces confounding
- Replication datasets
7. Weaknesses
- Fasting-insulin instruments largely reflect insulin resistance/adiposity (pleiotropy)
- Two authors
- Not about therapeutic insulin
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
MR assumptions (no horizontal pleiotropy) uncertain for fasting insulin.
9. Assessment of the statistical interpretation
CI log-symmetric (stats/C-INS-03_mr.py).
10. Relevance to the specific claim
Supports that higher endogenous insulin (insulin-resistance state) is linked to coronary disease, which is the correct kernel of the claim; it says nothing about insulin injections, which RCTs found neutral.
11. Independent contrary findings
12. Transferability to Germany and Europe
Directly applicable; same biology and clinical standards in Europe.
13. Overall methodological judgement
Supports the endogenous hyperinsulinaemia kernel; not evidence against insulin therapy.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | moderate |
| Directness | indirect |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | mixed |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
15. Linked fact checks
- Insulin (and injected insulin) is a principal driver of atherosclerosis. – Studies supporting the claim