The Study
Associations of Serum Folate and Vitamin B12 Levels With Cardiovascular Disease Mortality Among Patients With Type 2 Diabetes
This study found that people with type 2 diabetes who had very low or very high levels of certain vitamins (folate and B12) were more likely to die from heart problems—but it doesn’t prove the vitamins caused it. It’s like noticing that people who wear red shoes often trip; maybe red shoes are risky, or maybe they just happen to be worn by people who run a lot.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
For people with type 2 diabetes, having too little or too much vitamin B12 in the blood may raise the chance of dying from heart disease. Low folate is also risky, but high folate isn't.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 559 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — a 132% higher risk means nearly 2.5 times more likely to die from heart disease, which is very significant for patients managing diabetes.
- 2Low B12 (<369 pg/mL): 74% higher heart death risk.
- 3High B12 (≥703 pg/mL): 132% higher risk.
- 4Low folate (<7.1 ng/mL): 43% higher risk.
- 5High folate (≥19.5 ng/mL): no extra risk.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
JAMA Network Open
Year
2022
Authors
Yujie Liu, T. Geng, Z. Wan, Qi Lu, Xuena Zhang, Zixin Qiu, Lin Li, Kai Zhu, Liegang Liu, A. Pan, Gang Liu
Related Content
Claims (6)
In people with type 2 diabetes, having very high levels of vitamin B12 in the blood seems to be linked to a much higher chance of dying from heart disease—higher than at any other B12 level—so maybe high B12 isn’t helping, but instead signals something else wrong in the body.
For people with type 2 diabetes, having higher levels of folate (a B vitamin) in their blood doesn’t seem to make them more likely to die from heart disease, compared to people with moderate folate levels.
People with type 2 diabetes who have low levels of folate (a B vitamin) in their blood are 43% more likely to die from heart disease than those with moderate folate levels—so low folate might be linked to worse heart outcomes.
For people with type 2 diabetes, having too little or too much vitamin B12 in the blood might increase the chance of dying from heart disease — the safest range seems to be in the middle.
If your blood has too little or too much vitamin B12, you might be at higher risk of dying from any cause or from heart disease — the safest range is in the middle, between 190 and 948 pg/mL.
In people with type 2 diabetes, low folate might raise the risk of dying from heart disease because it leads to higher homocysteine, but high vitamin B12 affects heart disease risk on its own, no matter what homocysteine levels are.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.