Diabetic foot ulcer (DFU) is a form of chronic wound which becomes a serious complication in diabetes mellitus (DM). Recently, the role of vitamin D on T cell-mediated immunity, pancreatic insulin secretion, and its mechanism on cell growth and healing processes have been reported. This study aims to compare the vitamin D level of DM patients with DFU and without DFU to assess the duration and severity of DFU and its correlation with vitamin D levels. The sociodemographic characteristics and DFU duration were documented. The severity was examined in accordance with PEDIS classification. 25-hydroxyvitamin D (25[OH]D) was analysed using in-vitro chemiluminescent immunoassay (CLIA). Statistical analysis was performed and the P-value <.05 was considered as statistically significant. The vitamin D levels in DM patients with and without DFU were 8.90 ng/mL (6.52-10.90) and 16.25 ng/mL (13-19.59), respectively, with P < .001. There was no correlation between the duration of DFU and DFU severity by PEDIS score with vitamin D levels. Vitamin D levels in DM patients with DFU are lower than those in patients without DFU. However, there was insufficient evidence to conclude that there is no correlation between the DFU duration and DFU severity by PEDIS score with vitamin D levels.