The effects of hyperbaric oxygen therapy on insulin resistance – an approach to physiology

Mafalda Sampaio Alves^1,2*Inês Gomes-Alves^1,2Diogo Alpuim Costa^3,4,5,6,7João Sérgio Neves^8,9

• ¹Universidade do Porto Faculdade de Medicina, Porto, Portugal
• ²Unidade Local de Saude do Tamega e Sousa, Penafiel, Portugal
• ³Oncology Functional Unit, Hospital de Cascais Dr Jose de Almeida, Alcabideche, Portugal
• ⁴Haematology and Oncology Department, Rede CUF, Lisbon, Portugal
• ⁵Centro Hiperbárico de Cascais, Cascais, Portugal
• ⁶Universidade Nova de Lisboa Medical School, Lisbon, Portugal
• ⁷Universidade de Lisboa Faculdade de Medicina, Lisbon, Portugal
• ⁸Universidade do Porto Unidade de Investigacao e Desenvolvimento Cardiovascular, Porto, Portugal
• ⁹Department of Endocrinology, Diabetes and Metabolism, Centro Hospitalar Universitario de Sao Joao, Porto, Portugal

BACKGROUND: Diabetes mellitus (DM) is a severe, chronic and complex metabolic disease that leads to multiple dysfunctions, including micro and macrovascular complications, which are a major cause of morbidity and mortality. Complications related to hyperglycaemia are responsible for approximately 2.2 million deaths per year. Type 2 DM (TDM2) is highly preventable, and the stages that precede it are the ideal target for therapeutic intervention. Hyperbaric oxygen therapy (HBOT) is an established medical treatment for several clinical conditions, but it still lacks formal indications for DM-related comorbidities other than diabetic foot ulcers. Because DM is one of the most prevalent comorbidities in patients under HBOT, it has allowed the observation and inference of some of its effects on DM, suggesting clinical benefit in different spectrums of the disease. Our main aim was to gather the existing evidence on the impact of HBOT on insulin resistance, as this is the best predictor for the development of T2D. MATERIALS AND METHODS: The scoping review was the methodology chosen to include all available data. Exclusion criteria consisted of articles that did not mention the effects of HBOT on insulin resistance, described only the use of normobaric oxygen, or had no available translation to English, Spanish, or Portuguese. In addition, all data discussing any effects on insulin, insulin resistance, or insulin sensitivity were included. RESULTS: Two hundred and thirty studies were found, and 17 were eligible. The HBOT appears to improve fasting glycaemia and decrease insulin resistance in patients with DM, with effects appearing after 1 treatment session. Additionally, it reduces levels of proinflammatory cytokines that contribute to insulin resistance. The duration of this sensitisation effect remains unknown, as do the contributing molecular factors. CONCLUSIONS: HBOT seems to improve glycaemic levels and insulin sensitivity, thus presenting a potential treatment approach to treat insulin resistance and its consequences. However, translation into clinical practice remains contingent on robust, yet unavailable, randomised clinical trials.