Effects of a Single Bout of Interval Hypoxia on Cardiorespiratory Control and Blood Glucose in PatientsWith Type 2 Diabetes

OBJECTIVEdHypoxia may cause functional autonomic imbalance in diabetes. Intermittent hypoxia (IH), a technique improving the adaptation to hypoxia, might improve cardiorespiratory reflexes and, ultimately, blood glucose concentrations in patients with type 2 diabetes.We tested whether a single bout of IH could initiate a long-lasting response potentially leading to better adaptation to hypoxia. RESEARCH DESIGN AND METHODSdIn 14 patients with type 2 diabetes without autonomic complications, we measured blood pressure, heart rate, oxygen saturation, chemo-reflex (hypoxic and hypercapnic ventilatory responses, ventilatory recruitment threshold), and baroreflex sensitivity before, immediately after, and 3 and 6 h after a 1-h single bout of IH (6-min breathing of 13 % oxygenmixture 5 times each separated by 6-min recovery). The measurements were repeated on a placebo day (at least 1 week apart, in random sequence) when subjects were only breathing room air (single-blind protocol). RESULTSdIH significantly increased hypercapnic ventilatory responses and reduced venti-latory recruitment threshold, and increased oxygen saturation and blood pressures, whereas increases in heart rate variability and baroreflex sensitivity were not significant. Blood glucos