Hyperbaric oxygen therapy refers to the inhalation of 100% oxygen at a pressure greater than absolute atmospheric pressure. Both the therapeutic and toxic effects result from two therapeutic features: the mechanical loss of pressure increase and the physiological effects of hyperoxia. Hyperbaric oxygen therapy is an effective treatment for a variety of clinical conditions such as acute carbon monoxide poisoning, air embolism, soft tissue infections, radionecrosis, refractory osteomyelitis, thermal burns, skin grafts, crush injuries and impaired wound healing, such as “diabetic foot”. The main effects are to raise the partial pressure of oxygen, increase blood oxygen and tissue oxygen content; cause cerebral vasoconstriction, reduce cerebral edema and lower intracranial pressure; promote thrombus absorption; improve brain metabolism and restore brain function; and promote wakefulness. It is now believed that the toxicity of hyperbaric oxygen can be mediated by the production of oxygen free radicals, which cause lipid peroxidation and tissue damage. Hyperbaric oxygen exposure leads to an increase in the amount of dissolved oxygen in the blood, which causes an improvement in clinical symptoms. Some studies have reported that reactive oxygen species that cause cellular damage are associated with the pathogenesis of diabetes mellitus. During diabetes, persistent hyperglycemia promotes the production of reactive oxygen species through glucose autoxidation. Oxidative stress has also been associated with the diabetic state in animals and humans. Hyperbaric oxygen enhances superoxide dismutase activity due to intermittent or single HBO exposure and decreases superoxide dismutase activity with continued HBO exposure. Acute and repeated hyperbaric oxygen inhalation has been shown to modulate antioxidant enzyme activity in rat skeletal muscle, but this is dependent on the dosing regimen and muscle phenotype. DNA damaging effects were observed immediately after a single exposure to hyperbaric oxygen. No DNA damage was detected with distant treatment under the same conditions, suggesting an increased cellular defense of the body against oxidative stress.