Approximately 10-15 percent of individuals with diabetes mellitus develop foot ulcers, which precede 85 percent of amputations. Increased oxygen, through the use of hyperbaric oxygen therapy (HBOT), has been suggested to encourage ulcer healing thus reducing the risk of amputation. The objective of this systematic review is to evaluate the efficacy of systemic HBOT for nonhealing ulcers of the lower limb in diabetes patients. A systematic search, using controlled and keyword terms focusing on "HBOT" and "lower limb diabetic ulcers," was conducted. Databases searched included Medline, EMBASE, CINAHL, PubMed, Wiley’s Cochrane Library, and Biosis. Randomized controlled trials (RCTs) and observational studies were included. Pooled estimates of outcomes were determined when appropriate. Of the 654 citations identified, 157 articles underwent full-text review. Data were abstracted from twelve publications (six RCTs and six comparative observational studies). Pooled analysis of the RCT and observational data showed that treatment with HBOT reduced the risk of major amputation by 60 percent (p = .29) and 61 percent (p = .003) compared with standard wound care, respectively. The RCT data revealed that the relative risk of having an unhealed wound following HBOT was 0.54 (p = .10) and 0.24 (p < .0001) based on observational data. Due to the limited RCT evidence, it is not possible to conclusively establish the benefits and harms of treating diabetic lower limb ulcers with HBOT. No significant effects on amputation rates were found in the RCT evidence and in the high quality studies, no difference was found. O'Reilly, Pasricha, Campbell, Burke, Assasi, Bowen, Tarride, Goeree, (2013). Hyperbaric oxygen therapy for diabetic ulcers: systematic review and meta-analysis.¬†International journal of technology assessment in health care, 2013 Jul;29(3):269-81.¬†https://www.ncbi.nlm.nih.gov/pubmed/23863187