Diabetes mellitus type 2 (T2D) is characterized by insulin resistance of liver and skeletal muscle, which is at least partly due to impaired muscle mitochondrial function. Long-term HBO therapy, as applied for treating the diabetic foot syndrome, has been shown to improve blood glucose concentrations. To study the underlying mechanisms, we examined the short-term effect of HBO treatment on insulin sensitivity and mitochondrial oxidative capacity and production of reactive oxygen species (ROS) in a randomized, double blinded, placebo-controlled trial. Volunteers with type 2 diabetes (n=4; age 61±4 years; body mass index 30.2±2.2 kg/m2; HbA1c 7.0±0.7%) underwent two 2-hours sessions in a hyperbaric chamber of once with application of 100% oxygen (1.4 bar over atmospheric pressure [barO] for 20 min; HBO) and once with ambient air as placebo (21% oxygen; 1.4 barO; PLC). Tissue-specific insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamps with stable isotope dilution, while muscle oxygen fluxes were measured with high resolution respirometry. After HBO treatment, hepatic insulin sensitivity was higher (insulin-mediated suppression of endogenous glucose production: 69.7±0.1% vs. PLC 55.3±3.2%, p<0.05), whereas peripheral insulin sensitivity was comparable (2.0±0.3 vs. 2.2±0.3 mg*kg-1*min-1, p=0.24). Muscle ROS production markedly increased after HBO (increase in ROS: 73±3% vs. PLC -14±5%; p<0.005), while mitochondrial oxidative capacity only tended to be lower after HBO.
In conclusion, a single session of HBO treatment already improves hepatic insulin resistance and stimulates muscle ROS release, which may activate antioxidative defense, both of which could contribute to improved glycaemia upon chronic treatment.
T. Sarabhai: None. E. Anadol-Schmitz: None. H. Katsuyama: None. D.F. Markgraf: Research Support; Self; Sanofi. L. Busch: None. R. Guthoff: None. J. Schneppendahl: None. M. Roden: Advisory Panel; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Poxel SA, Servier. Board Member; Self; Eli Lilly and Company. Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Sanofi. Speaker's Bureau; Self; Novo Nordisk Inc.