Objective

Because vitamin D deficiency is associated with diabetes and insulin resistance, and the triglyceride-glucose (TyG) index is a reliable marker of metabolic health, this study aimed to clarify the association between vitamin D status and the TyG index.
Methods
A cross-sectional analysis was conducted on 4,819 participants from the 2022 Korea National Health and Nutrition Examination survey, stratified by age and sex. Vitamin D deficiency was defined as blood 25-hydroxyvitamin D3 (25(OH)D3) <20 ng/mL, and a metabolically unhealthy state as a TyG index of ≥8.82 and ≥8.73 for men and women, respectively.
Results
Approximately 46.9% of South Korean adults were vitamin D deficient, and 35.5% were metabolically unhealthy. After adjustment, blood 25(OH)D3 levels were inversely correlated with the TyG index in younger women (β=−0.004, standard error [SE]=0.002, P=0.039), middle-aged men (β=−0.006, SE=0.003, P=0.015), and older men (β=−0.008, SE=0.002, P=0.002). Vitamin D deficiency was associated with a higher risk of a metabolically unhealthy state in middle-aged men (odds ratio [OR], 1.59; 95% confidence interval [CI], 1.11−2.28) and older men (OR, 2.15; 95% CI, 1.31−3.55).
Conclusion
These findings suggest that adequate vitamin D status may help maintain a metabolically healthy state, and the TyG index may help identify vitamin D insufficiency or deficiency, particularly in middle-aged and older South Korean men.