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Title: Glucose metabolism during and following acute hypoxia and exercise in individuals with Type 2 diabetes
Author: Mackenzie, Richard W. A.
ISNI:       0000 0004 2688 2443
Awarding Body: University of Brighton
Current Institution: University of Brighton
Date of Award: 2009
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The current work is novel in that it investigated in vivo analysis of glucose metabolism following hypoxic exposure in type 2 diabetics. Using moderate levels of hypoxia (O2 ~ 14.8%; equivalent ~3100 m), study one found that 60 minutes of resting hypoxic exposure reduced blood glucose concentrations [mean (SEM): -0.74 (0.14) mmol/l]; (P = 0.002)] in type 2 diabetics. Arterialised blood glucose concentrations were also found to be lower in the 4 hour following hypoxic exposure when compared to the normoxic condition (P = 0.001). The second study compared the combined effects of hypoxia and moderate intensity exercise (Hy Ex) vs. exercise in normoxia (Nor Ex). The total area under the curve for insulin (AUCIns) was also significantly lower subsequent to an intravenously administered glucose load in the 4 hours following Hy Ex when compared to the Nor Ex trial [mean (SEM): Hy Ex; 4334 (617) vs. Nor Ex; 5637 (820) µU∙ml-1∙min], respectively (P = 0.007). The third study demonstrated that glucose disposal was acutely enhanced in exercise bouts lasting 60 (Hy Ex60; P = 0.000) and 40 (Hy Ex40; P = 0.005) minutes (of equal work) in hypoxia. Indices of insulin resistance and insulin sensitivity were also improved in the 48 hours following both Hy Ex60 and Hy Ex40, indicating that insulin-dependent mechanisms were affected. The results from study 4 suggest that intermittent exercise in hypoxia [Hy (5:5)] may acutely encourage glucose disposal and provide moderate-term improvements in glycaemic control (~24 hours). Indices of insulin resistance and sensitivity were not changed following intermittent exercise in normoxia [Nor (5:5)]. Continuous moderate intensity exercise in hypoxia (Hy Ex60) demonstrated the greatest improvements in glucose tolerance with plasma insulin (P = 0.025), homeostasis model for insulin resistance (HOMAIR; P = 0.028) and fasting insulin resistance Index (FIRI; P = 0.028) all improved in the 48 hours following exercise. The conclusions drawn are fourfold 1) hypoxia has the ability to increase glucose disposal, both during and following acute exposure and that; 2) the effects of exercise on glucose disposal are enhanced by moderate hypoxia; 3) improvements in insulin sensitivity may contribute to hypoxic-induced glucose transport activity; and 4) intermittent exercise can acutely improve glucose control. The finding that hypoxia alters glucose metabolism is in keeping with the original hypothesis and suggests a clinical role for hypoxia in the treatment of type 2 diabetes.
Supervisor: Watt, Peter ; Brickley, Gary ; Maxwell, Neil Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: C600 Sport and Exercise Science