Hyperbaric Treatment With Normal Air Prevents The Progression Of Hyperglycemia In Type 2 Diabetes

Abstract

Previous study reported that hyperbaric treatment with 36% oxygen decreases glucose and insulin level in type 2 diabetes rats, and the improvement could be due to increased oxygen saturation and blood flow during hyperbaric treatment. However, the effects of simple hyperbaric treatment without high oxygen remain unknown. PURPOSE: To investigate the effects of hyperbaric treatment with normal air on hyperglycemia in type 2 diabetes, focusing on skeletal muscle hemodynamics. METHODS: 24-week-old male Otsuka Long-Evans Tokushima fatty (OLETF) rats and Long-Evans Tokushima Otsuka (LETO) rats were used as diabetes model and non-diabetes model, respectively. All rats were assigned to hyperbaric treatment or non-treatment groups. The rats in the hyperbaric treatment group were exposed to hyperbaric chamber at 1.3 ATA with normal air for 8 hours a day for 16 weeks. The oxygen saturation and total-hemoglobin (Hb) changes in the calf muscle during hyperbaric treatment was measured by near-infrared spectroscopy. Oral glucose tolerance test was performed at 40-week-old. RESULTS: Oxygen saturation and total-Hb were significantly increased during hyperbaric treatment from 73.3 to 76.7% and 25.0 to 26.3×104/mm3 in OLETF rats, 71.1 to 74.8% and 20.1 to 22.5×104/mm3 in LETO rats (p<0.05). The glucose and insulin levels were significantly higher in OLETF rats than LETO rats at both fasting and after glucose administration (p<0.05). Among OLETF rats, the glucose levels at 30, 60, 120 min after glucose administration were significantly lower in the hyperbaric treatment group than the non-treatment group (30 min: 325 ± 71 vs. 385 ± 48, 60 min: 332 ± 67 vs. 421 ± 111, 120 min: 216 ± 45 vs. 230 ± 20 mg/dL, p<0.05). Additionally, the fasting insulin level and the levels at 120 min after glucose administration were significantly lower in the hyperbaric treatment group than the non-treatment group (Fasting: 3.6 ± 1.1 vs. 4.3 ± 2.7, 120 min: 4.4 ± 1.6 vs. 5.2 ± 3.9 ng/mL, p<0.05). CONCLUSIONS: The present study demonstrated that hyperbaric treatment with normal air also prevents the progression of hyperglycemia in OLETF rats, and the treatment without high oxygen increases oxygen saturation and blood flow in the skeletal muscle.