Training under normoxia and normobaric hypoxia in patients with type 1 diabetes

Apart from insulin, physical exercise is a crucial component of therapy in patients with type 1 diabetes mellitus (T1DM). The benefits of physical activity in such patients include improved insulin sensitivity, lowered blood glucose, reduced body fat and improved cardiovascular function and physical performance. Hypoglycemia is a crucial issue in the peri-training period in insulin-treated patients. Proper preparation for exercise is the key to reducing the risk of hypoglycemia. The selection of the training type and the patient's knowledge of the effect of such training on glycemia are also significant. Physical exercise under normobaric hypoxia in the training rooms is also available commercially and is becoming increasingly popular. Under such conditions, the air consists of 15.4% oxygen and 84.5% nitrogen, which corresponds to the conditions at an altitude of approximately 2,500 meters above sea level. Hypoxia induces the production of the hypoxia-inducible factor (HIF-1), which regulates the expression of over 100 genes. It modulates key metabolic pathways to optimize glucose utilization by increasing cell sensitivity to insulin, more efficient glucose uptake from the blood and activating effect on glycolytic enzymes. Additionally, HIF-1 shows beneficial effects on the lipid profile, vascular endothelium and performance as measured by the maximal oxygen uptake (VO2max). The aim of this paper was to review and summarize the most recent studies on the effects of exercise on glycemic control and physical performance under normoxia and normobaric hypoxia in patients with T1DM.