The Multi-Dimensional Role of Vitamin D in the Pathophysiology and Treatment of Diabetic Foot Ulcers: From Molecular Mechanisms to Clinical Translation.

Diabetic foot ulcers (DFUs) constitute a severe and debilitating complication of diabetes, imposing a substantial global health burden due to their intricate pathophysiology and impaired wound healing processes. Vitamin D deficiency is highly prevalent among diabetic populations, and accumulating evidence indicates its potential involvement in the pathogenesis and prognosis of DFUs. This review comprehensively explores the diverse roles of vitamin D in DFUs, encompassing its molecular mechanisms such as immunomodulation, promotion of angiogenesis, neuroprotection, and induction of antimicrobial peptides, as well as the metabolic characteristics associated with various vitamin D forms and compromised vitamin D receptor (VDR) signaling pathways. Although robust observational studies have established an association between vitamin D deficiency and adverse outcomes in DFUs, the clinical validation of supplementation efficacy through randomized controlled trials (RCTs) remains constrained by limitations such as small sample sizes, heterogeneity in study protocols, and insufficient long-term follow-up. This highlights the critical need for large-scale, high-quality studies to ascertain optimal treatment regimens and to cater to individualized patient requirements, particularly for individuals with obesity or those with renal impairments. Innovative strategies, such as the topical administration of vitamin D through intelligent delivery systems leveraging advanced biomaterials like nanofibers and hydrogels, exhibit substantial preclinical potential in enhancing stability, achieving targeted controlled release, and augmenting local biological effects, including the induction of antimicrobial peptides. Nevertheless, significant challenges persist in conclusively establishing clinical efficacy, comprehensively elucidating the underlying mechanisms, ensuring the safe translation of novel delivery systems, and developing personalized therapeutic strategies. The future success of these interventions hinges on meticulous research and interdisciplinary collaboration to seamlessly integrate validated vitamin D-based interventions into a comprehensive multidisciplinary management framework for DFUs, thereby holding promise for improving the clinical outcomes of this debilitating condition.