Background: Diabetes mellitus is one of the most common metabolic diseases. The most serious complication of diabetes is diabetic foot ulcer, which affects several million people around the world each year. In recent years, increasingly modern methods of physical medicine including hyperbaric oxygen therapy have been used often in the complex therapy of this complication. Methods: This study included 45 patients, 24 male (53.3%) and 21 female (46.6%), whose age was between 49 and 83 years (mean age: 66.7 ± 8.8 years) with diabetes lasting for 1.5-18 years, who underwent local hyperbaric oxygen therapy at the pressure of 2.5 ATA (30 exposures for 30 min each) due to diabetic foot ulcers. The progress in wound healing before and after the end of therapy was evaluated by computerized planimetry, and the pain intensity was assessed with the use of a VAS. Results: The analysis of results showed a statistically significant reduction in the wound surface area after the treatment, from 8.54 ± 3.34 cm to 4.23 ± 3.23 cm² (p = 0.000001). In 5 patients (11.1%), the wounds were healed completely. In 25 patients (55.5%), the topical state of the wound surface was significantly decreased by 50% on average. There was also a significant reduction in the perceived pain on the VAS in all examined patients from 4.64 ± 1.68 points before treatment to 1.51 ± 0.92 points after treatment (p = 0.000001). Conclusions: The application of local HBO therapy in the treatment of diabetic foot ulcers accelerates the ulcer healing process, as judged in objective planimetric assessment, and reduces the intensity of perceived pain ailments.