Meta-analysisindependent cross-checkabstract checked★ key study I-WHT-112 in-depth review
High-glycaemic diets were linked to 27% more type 2 diabetes
Association of glycaemic index and glycaemic load with type 2 diabetes, cardiovascular disease, cancer, and all-cause mortality: a meta-analysis of mega cohorts of more than 100 000 participants.
Overview
Jenkins DJA et al.. Lancet Diabetes Endocrinol 2024 · PMID 38272606 · DOI 10.1016/S2213-8587(23)00344-3
In ten very large cohorts, people with the highest dietary glycaemic index had 27% higher diabetes risk.
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?
GI/GL and chronic disease.
- How was the study done?
Meta-analysis of mega-cohorts.
- How many people, animals or samples were studied?
10 cohorts.
- What was actually found?
High GI linked to T2D, CVD.
- How large was the observed effect?
RR 1.27 for T2D.
- What do the results mean in everyday life?
Carbohydrate quality matters.
- What are the study's limitations?
Fixed-effect, observational.
- What does it say about Elawady's specific claim?
Supports direction; not specific to wheat.
- Do the results apply to Germany and Europe?
Moderate-high.
- What can explicitly not be concluded from this study?
Cannot prove causation.
Scientific in-depth review
1. Full reference
- Authors
- Jenkins DJA et al.
- Journal
- Lancet Diabetes Endocrinol
- Year
- 2024
- Identifier
- PMID 38272606 DOI 10.1016/S2213-8587(23)00344-3
- 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
First author declared research grants and in-kind support from many food companies (e.g. Barilla, Quaker, Kellogg Canada) and the Soy Nutrition Institute; funded by Banting and Best and the Karuna Foundation.
2. Research question
Are glycaemic index and load associated with T2D, CVD, diabetes-related cancers and mortality?
3. Study design and population
- Study design
- Meta-analysis – Meta-analysis of mega-cohorts (>=100,000 participants)
- Population
Participants of 10 large cohorts
- Country
USA (6), Europe (1), Asia (2), international (1)
- Period
Searches to 4 August 2023
- Sample size
10 cohorts, 48 studies
- Inclusion and exclusion criteria
Prospective cohorts >=100,000 participants
4. Methods and endpoints
- Exposure / intervention
Highest GI/GL quantile
- Comparator
Lowest quantile
- Endpoints
T2D, total CVD, diabetes-related cancer, all-cause mortality
- Statistical methods
Fixed-effect pooling of most-adjusted RRs
5. Actual results
- Results
High GI: T2D RR 1.27 (1.21-1.34), CVD 1.15 (1.11-1.19), diabetes-related cancer 1.05 (1.02-1.08), all-cause mortality 1.08 (1.05-1.12). High GL: T2D 1.15 (1.09-1.21), CVD 1.15 (1.10-1.20). Associations with fibre and whole grains similar to low GI.
- Absolute risks
not reported
- Authors' conclusion
Recommendations to reduce GI/GL could have effects similar to recommendations to increase fibre and whole grain.
6. Strengths
- Large cohorts
- Registered protocol
7. Weaknesses
- Fixed-effect model
- Observational
- Author COIs; GI research group
8. Risk of bias
- Orienting tool
- AMSTAR 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Fixed-effect pooling understates uncertainty.
9. Assessment of the statistical interpretation
CIs log-symmetric; fixed-effect model makes CIs narrow (stats/C-WHT-05).
10. Relevance to the specific claim
Supports that high-GI diets are associated with ~27% higher T2D risk; does not single out white flour.
11. Independent contrary findings
Reynolds 2019 (I-WHT-01) graded GI/GL evidence low to very low.
12. Transferability to Germany and Europe
Moderate-high.
13. Overall methodological judgement
Supportive but not decisive.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | high |
| Directness | direct |
| Reproducibility | replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | moderate |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Causality.