As for the NDFO group and the DFO group, serum 25(OH)VD levels were positively correlated with mean sunshine duration per day, ulcer time, Wagner grade, infection severity, recurrence of foot ulcer, HDL-C, P-IL-10, T-IL-10, and T-VDR expression levels (P < 0.05). The gene discussed is IL10; the disease is ulcer disease.