Cyclic Hypobaric Hypoxia Improves Markers of Glucose Metabolism in Middle-Aged Men

Marquez, Juan L., Scott Rubinstein, Jill A. Fattor, Omer Shah, Andrew R. Hoffman, and Anne L. Friedlander. Cyclic hypobaric hypoxia improves markers of glucose metabolism in middle-aged men. High Alt Med Biol 14:263272, 2013.Chronic hypoxia increases dependence on glucose in men and increases insulin sensitivity in men and women. Cyclic Variations in Altitude Conditioning (CVAC) is a novel technology that provides exposure to rapidly fluctuating cyclic hypobaric hypoxia (CHH). Purpose: To test the hypothesis that markers of glucose metabolism would change with CVAC CHH, two groups of middle-aged men were exposed to 10 weeks (40min/day, 3 day/week) of either CHH or sham (SH) sessions. Methods: CHH subjects (age: 48 +/- 6, weight: 86 +/- 12kg, BMI: 27.1 +/- 3, n=11) experienced cyclic pressures simulating altitudes ranging from sea level to 3048m (week 1) and progressing to 6096m (by week 5 through week 10). SH subjects (age: 50 +/- 4, weight: 89 +/- 15kg, BMI: 27.5 +/- 3, n=10) were exposed to slowly-fluctuating pressures up to 607m (all subjects blinded to elevation). Physical function and blood markers of glucose metabolism were measured at baseline, 3, 6, and 10 weeks. Results: Two CHH subjects were dropped from analysis for failure to progress past 3048m (CHH: n=9). Weight and physical activity remained stable for both groups. There was a group-by-time interaction in fasting glucose (CHH: 96 +/- 9 to 91 +/- 7mg/dL, SH: 94 +/- 7 to 97 +/- 9mg/dL, p<0.05). Reduction in plasma glucose response to oral glucose tolerance test [area under the curve] was greater in CHH compared to SH after 10 weeks of exposure (p<0.03). Neither group experienced changes in fasting insulin, insulin response during the OGTT, or changes in a timed walk test. Conclusion: Ten weeks of CVAC CHH exposure improves markers of glucose metabolism in middle-aged men at risk for metabolic syndrome.