Vitamin D status in relation to lower extremity arterial plaque and diabetic foot ulcers in type 2 diabetes

ObjectivesLimited evidence exists regarding the association of vitamin D status with lower extremity arterial plaque progression and diabetic foot ulcer outcomes. This study investigated the relationship between vitamin D status and the risk of lower extremity arterial plaque progression and diabetic foot ulcer development.MethodsIn this cross-sectional analysis of 7476 consecutively hospitalized type 2 diabetes patients (2018-2024), serum 25-hydroxyvitamin D level was measured using the electrochemiluminescence method. Vitamin D deficiency (<20 ng/mL) and insufficiency (20-30 ng/mL) were defined per the Endocrine Society guidelines. Lower extremity arterial plaque was identified using arterial Doppler ultrasonography, and diabetic foot ulcer was diagnosed using the International Working Group on the Diabetic Foot 2019 criteria. Multivariate logistic regression and receiver operating characteristic analyses were used to evaluate associations between parameters.ResultsDecreased 25-hydroxyvitamin D levels were correlated with adverse lipid profiles (high-density lipoprotein cholesterol: r = 0.152, P < 0.001) and elevated inflammatory markers (high-sensitivity C-reactive protein: r = -0.086, P < 0.001). Lower extremity arterial plaque patients (n = 4622) exhibited longer diabetes duration, higher glycosylated hemoglobin levels, and reduced 25-hydroxyvitamin D levels compared with those without lower extremity arterial plaque (19.98 vs. 23.41 ng/mL, P < 0.001). The prevalence of diabetic foot ulcer in lower extremity arterial plaque patients was 2.8%, and the levels of 25-hydroxyvitamin D were significantly lower in diabetic foot ulcer patients than in nondiabetic foot ulcer patients (14.77 vs. 19.98 ng/mL, P < 0.001). Adjusted models revealed that 25-hydroxyvitamin D level was an independent protective factor against lower extremity arterial plaque (odds ratio = 0.938, 95% confidence interval: 0.914-0.963) and diabetic foot ulcer (odds ratio = 0.938, 95% confidence interval: 0.932-0.944). Receiver operating characteristic curve analysis demonstrated that a 25-hydroxyvitamin D level ≤18.94 ng/mL predicted lower extremity arterial plaque, with an area under the curve value of 0.651, which improved to 0.703 when combined with the duration of diabetes and white blood cell count. For diabetic foot ulcer prediction, a 25-hydroxyvitamin D level ≤17.11 ng/mL achieved an area under the curve value of 0.674, which increased to 0.764 after adjusting for covariates.ConclusionVitamin D insufficiency is independently associated with lower extremity arterial plaque severity and incident diabetic foot ulcer in type 2 diabetes. Therapeutic implications of vitamin D supplementation warrant prospective investigation.