Background/Objectives: Vitamin D plays an important role in glucose metabolism, lipid regulation, and inflammatory processes, and has been implicated in cardiometabolic health. However, its associations with specific metabolic biomarkers remain inconsistent, particularly in older adults. This study aimed to examine whether vitamin D deficiency is differentially associated with multiple metabolic biomarkers in a nationally representative sample of older adults. Methods: This cross-sectional study used data from the 2024 Korea National Health and Nutrition Examination Survey, including 1806 adults aged ≥65 years. Vitamin D deficiency was defined as serum 25-hydroxyvitamin D levels < 20 ng/mL. Metabolic biomarkers included fasting glucose, glycated hemoglobin (HbA1c), triglycerides, C-reactive protein (CRP), high-density lipoprotein cholesterol (HDL-C), waist circumference, and body mass index (BMI). Complex sample linear regression analyses were performed with sequential adjustment for sociodemographic factors, health behaviors, and comorbidities. Results: In unadjusted analyses, vitamin D deficiency was associated with adverse metabolic profiles, including higher fasting glucose, HbA1c, triglycerides, waist circumference, and CRP levels, and lower HDL-C levels. After adjustment for sociodemographic factors, health behaviors, and comorbidities, significant associations remained for HbA1c (β = 0.10, p = 0.034), triglycerides (β = 0.10, p = 0.003), and waist circumference (β = 1.21, p = 0.040). No significant associations were observed for fasting glucose, HDL-C, CRP, or BMI. Conclusions: Vitamin D deficiency was independently associated with poorer long-term glycemic status, hypertriglyceridemia, and central adiposity in older adults, but not with other metabolic markers after adjustment. These findings suggest that the metabolic correlates of vitamin D deficiency may be domain-specific rather than generalized. Longitudinal and interventional studies are needed to clarify causality and underlying mechanisms.
Kim et al. (Thu,) studied this question.