The present study aimed at examining beneficial effects of intermittent
hypoxia training (IHT) under prediabetic conditions. We investigate the effects of three-week IHT on
blood glucose level, tolerance to acute
hypoxia, and leukocyte
mRNA expression of
hypoxia inducible factor 1α (HIF-1α) and its target genes, i.e.
insulin receptor, facilitated
glucose transporter-solute carrier family-2, and
potassium voltage-gated channel subfamily J. Seven healthy and 11 prediabetic men and women (44-70 years of age) were examined before, next day and one month after three-week IHT (3 sessions per week, each session consisting 4 cycles of 5-min 12% O2 and 5-min room air breathing). We found that IHT afforded beneficial effects on
glucose homeostasis in patients with
prediabetes reducing fasting
glucose and during standard oral
glucose tolerance test. The most pronounced positive effects were observed at one month after IHT termination. IHT also significantly increased the tolerance to acute
hypoxia (i.e. SaO2 level at 20th min of breathing with 12% O2) and improved functional parameters of respiratory and cardiovascular systems. IHT stimulated HIF-1α
mRNA expression in blood leukocytes in healthy and prediabetic subjects, but in
prediabetes patients the maximum increase was lagged. The greatest changes in
mRNA expression of HIF-1α target genes occurred a month after IHT and coincided with the largest decrease in
blood glucose levels. The higher expression of HIF-1α was positively associated with higher tolerance to
hypoxia and better
glucose homeostasis. In conclusion, our results suggest that IHT may be useful for preventing the development of
type 2 diabetes. Impact statement The present study investigated the beneficial effects of intermittent
hypoxia training (IHT) in humans under prediabetic conditions. We found that three-week moderate IHT induced higher HIF-1α
mRNA expressions as well as its target genes, which were positively correlated with higher tolerance to acute
hypoxia and better
glucose homeostasis in both middle-aged healthy and prediabetic subjects. This small clinical trial has provided new data suggesting a potential utility of IHT for management of
prediabetes patients.