Olfactory Dysfunction and Metabolic Syndrome Components: A Systematic Review and Meta-Analysis.
Neeti Gandra, Kaitlyn A Roberts, Shaun A Nguyen et al.
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In 30 seconds
This systematic review and meta-analysis examined associations between olfactory dysfunction (OD) and metabolic syndrome components. Of 4045 studies screened, 47 were included in the analysis. Participants with OD had greater odds of diabetes (OR = 1.2, p < 0.0001) and higher fasting glucose (MD +0.8 mg/dL; p < 0.00001), alongside differences in cholesterol measures and cardiometabolic comorbidities. Conversely, people with diabetes or elevated BMI had lower olfactory TDI composite scores. The findings indicate associations in both directions but do not establish causality.
Key findings
- OD was associated with greater odds of diabetes (OR = 1.2, p < 0.0001), atrial fibrillation (OR = 1.7, p < 0.00001), and heart failure (OR = 1.6, p = 0.008).
- Adults with OD had higher fasting glucose (MD +0.8 mg/dL; p < 0.00001), lower total cholesterol (MD -6.0 mg/dL; p = 0.04), and lower HDL levels (MD -1.8 mg/dL; p < 0.00001).
- Diabetes and elevated BMI were associated with lower TDI composite scores (MD -5.6; p < 0.00001 and MD -2.8; p < 0.00001, respectively).
Why it matters
The review links olfactory impairment with several metabolic and cardiovascular conditions, while metabolic disorders are also associated with poorer olfactory test scores. Recognising this overlap may help clinicians consider olfactory function and metabolic health together when assessing relevant patients. The evidence describes associations, however, and does not show that either condition causes the other.
What to keep in mind
The review synthesises associations across included studies; these findings cannot establish causality.