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Substrate source utilization during moderate intensity exercise with glucose ingestion in Type 1 diabetic patients
M Robitaille1, M-C Dubé, S J Weisnagel
1Département de chimie-biologie et des sciences de l'activité physique, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada G9A 5H7.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|April 14, 2007
Summary
Diabetic patients show similar overall carbohydrate and fat oxidation during exercise compared to controls. However, they utilize less plasma glucose and more muscle glycogen, indicating altered fuel metabolism.
Area of Science:
- Exercise Physiology
- Metabolic Research
- Diabetes Mellitus
Background:
- Understanding substrate utilization during exercise is crucial for managing diabetes.
- Diabetic patients often exhibit altered metabolic responses compared to healthy individuals.
Purpose of the Study:
- To compare substrate oxidation, including exogenous glucose, liver-derived glucose, and muscle glycogen, during exercise in diabetic patients and control subjects.
- To investigate the impact of pre-exercise glucose ingestion on fuel utilization in type 2 diabetes.
Main Methods:
- Indirect respiratory calorimetry and stable isotope tracer techniques were employed.
- Eight diabetic patients and eight control subjects performed a 60-minute cycling exercise at moderate intensity.
- Subjects ingested a standardized breakfast and a labeled glucose load prior to exercise.
Main Results:
- Overall carbohydrate and fat oxidation rates were not significantly different between groups.
- Exogenous glucose oxidation was similar in both diabetic and control groups.
- Diabetic patients exhibited significantly lower plasma glucose and liver-derived glucose oxidation.
- Muscle glycogen oxidation was significantly higher in diabetic patients compared to controls.
Conclusions:
- Despite similar overall substrate oxidation, diabetic patients demonstrate impaired plasma glucose utilization during exercise.
- A compensatory increase in muscle glycogen utilization occurs in diabetic patients when glucose is administered before exercise.
- These findings highlight distinct metabolic adaptations in diabetic individuals during physical activity.
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