Decreased expression of 25-hydroxyvitamin D in peripheral plasma and vitamin D receptor in wound margin tissue associated with diabetic foot ulcers in patients with type 2 diabetes mellitus

Abstract Background There are no clinical studies have attempted to elucidate the correlation between vitamin D deficiency and the incidence of diabetic foot osteomyelitis (DFO) .This study to elucidate the expression of 25-hydroxyvitamin D (25(OH)VD) in peripheral plasma (P-25(OH)VD) and vitamin D receptor (VDR) in wound margin tissues (T-VDR) of patients with type 2 diabetes mellitus (T2DM) who presented with diabetic foot ulcer (DFU) and DFO, and identify its correlation with treatment outcomes of DFU and DFO. Methods 156 T2DM patients with DFU (DFU group), 100 newly diagnosed T2DM patients without DFU (T2DM group), and 100 healthy controls (NC group). DFU group were further categorized into DFO (n = 80) and NDFO subgroups (n = 76). Expression levels of P-25(OH)VD were measured via chemiluminescence, and T-VDR was measured through quantitative real-time PCR. Results DFU group showed significantly lower P-25(OH)VD expression than in the T2DM group (P < 0.05). DFO group showed significantly lower P-25(OH)VD and T-VDR expression than those in the NDFO group (P < 0.05). Furthermore, P-25(OH)VD and T-VDR expression of DFU group were negatively correlated with ulcer course, Wagner grade, wound infection severity, the detection rate of drug-resistant bacteria, recurrence rate, and amputation rate of foot ulcer (P < 0.05). However, P-25(OH)VD and T-VDR expression were positively correlated with ulcer healing rate after 8 weeks (P < 0.05). Low expression of P-25(OH)VD were an independent risk factor for DFU and DFO (ORDFU = 2.42, ORDFO = 3.05, P < 0.05), and low expression of T-VDR was an independent risk factor for DFO (OR = 2.83, P < 0.05). The area under the ROC curve (AUC) of 25(OH)VD related to the diagnosis of DFU and DFO was 0.821 (95% CI: 0.754 – 0.886, P < 0.001) and 0.786 (95%CI: 0.643 – 0.867, P < 0.001), When establishing a diagnosis of DFO, the AUC of T-VDR was 0.703 (95%CI: 0.618 – 0.853, P < 0.001). Conclusions Decreased expression of P-25(OH)VD and T-VDR of T2DM patients are closely related to the occurrence, development, and prognosis of DFU and DFO, which can consequently be applied as potential biomarkers and be used to predict DFU and DFO.