Sprinting as a clinical tool for the prevention of exercise-mediated hypoglycaemia in Type 1 Diabetes Mellitus

Vanessa Bussau

    Research output: ThesisDoctoral Thesis

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    [Truncated] Despite the numerous physiological and psychological health benefits of a physicallyactive lifestyle for individuals with type 1 diabetes, the risk of hypoglycaemia increasesboth during and after exercise. It is important to note, however, that not all types ofexercise result in an elevated risk of hypoglycaemia. For instance, prolonged highintensityaerobic exercise in these individuals result in an increase in glycaemia duringand after exercise. This raises the intriguing possibility that this type of exercise might bebeneficial if adopted to counter a fall in glycaemia in complication-free individuals withtype 1 diabetes, thus helping to prevent or delay hypoglycaemia if no carbohydrate isreadily available. Unfortunately, this type of exercise modality to prevent hypoglycaemiais unlikely to be well tolerated by most individuals with type 1 diabetes due to theimpractical duration of this type of exercise. This raises the primary aim at the core ofthis thesis to determine whether a much shorter bout of exercise lasting only 10 sec andperformed at maximal intensity could be adopted to prevent glycaemia from falling. Forthis reason, the primary goal of this thesis was to determine whether a 10-sec maximalsprint effort performed after (Chapter 3) or before (Chapter 4) moderate intensity exerciseprovides a possible means other than carbohydrate intake to prevent glycaemia fromfalling when exercise is performed under hyperinsulinaemic conditions by complicationfreeindividuals with type 1 diabetes. Also, given that for this type of study, it is commonpractice to subject participants to a graded exercise test to set exercise intensity relativeto VO2peak, a secondary objective of this thesis was to determine whether the risk ofhypoglycaemia is increased early during recovery from this type of exercise protocol(Chapter 2). Finally, since the counterregulatory response to sprinting has not beenexamined in hyperinsulinaemic individuals with type 1 diabetes, thus making it difficultto compare the findings of Chapters 3 and 4 with the literature, our last aim was toexamine the counterregulatory responses to sprinting in type 1 diabetic individuals underhyperinsulinaemic conditions (Chapter 5).

    The first study of this thesis (Chapter 2) examines whether the risk of hypoglycaemiaincreases in response to graded exercise testing in individuals with type 1 diabetes. Eightnon-diabetic male participants and seven complication-free type 1 diabetic maleindividuals in good glycaemic control were recruited. On the morning of testing, thediabetic participants followed their normal insulin regimen, and both groups ate theirusual breakfast. Then, participants were subjected to graded exercise testing approximately four hours later. We found that this type of exercise result in a rapid postexerciseincrease in blood glucose levels (> 2 mM), which remain elevated for the firsttwo hours of recovery. On clinical grounds, these findings suggest for the first time thatthe early post-exercise risks of hypoglycaemia associated with graded exercise testing areminimal when performed under near basal plasma insulin levels, with no carbohydrateadministration required soon before or after testing to prevent hypoglycaemia.

    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2015


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