The incidence of hypoglycemia during HBO₂ therapy: A retrospective review

Background: Hypoglycemia is concerning in patients with diabetes undergoing hyperbaric oxygen (HBO₂) therapy. We aimed to estimate the incidence, risk factors and a pretreatment glucose threshold of HBO₂-associated hypoglycemia. Methods: We retrospectively evaluated a patient cohort undergoing HBO₂ therapy. We calculated the area under the curve (AUC) and odds ratio (OR) with 95% confidence interval (CI) adjusting for patients' age, gender, diabetes type, insulin use, body mass index, hemoglobin A1c and HBO₂ treatment time. Results: During 77 months, 3,136 HBO₂ sessions were performed on patients with diabetes. In-chamber glucose was higher than pre-HBO₂ glucose in 1,708/3,136 sessions (54%). The incidence of hypoglycemia (defined as ≤70 mg/dL) during or immediately after HBO₂ treatment was 1.5% (0.8-2.1%). Hypoglycemia that was symptomatic or severe was rare. A glucose value pre-HBO₂ of 150 mg/dL best predicted the risk of subsequent hypoglycemia (AUC 0.80; 95% CI, 0.75-0.86). Type 1 diabetes was independently associated with increased risk of hypoglycemia (OR 3.69; 95% CI, 1.67, 8.19) whereas insulin use was not. Conclusions: In patients with diabetes undergoing HBO₂, severe hypoglycemia is rare and occurs more frequently in Type 1 diabetes. Pre-HBO₂ glucose values may be used to predict subsequent hypoglycemia and reduce the need for routine glucose monitoring during and after HBO₂.