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Hyperglycemia stimulates carbohydrate oxidation in humans
H Yki-Järvinen1, C Bogardus, B V Howard
1Clinical Diabetes and Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, Arizona 85016.
The American Journal of Physiology
|October 1, 1987
Summary
Hyperglycemia (high blood glucose) and insulin both increase carbohydrate oxidation in humans. However, insulin is a more potent stimulator of carbohydrate oxidation than glucose alone.
Area of Science:
- Metabolic Physiology
- Human Metabolism
- Endocrinology
Background:
- Insulin is a primary regulator of glucose metabolism.
- The independent effects of glucose and insulin on carbohydrate oxidation require further elucidation.
Purpose of the Study:
- To determine if hyperglycemia stimulates carbohydrate oxidation independently of insulin.
- To compare the stimulatory effects of glucose and insulin on carbohydrate oxidation.
Main Methods:
- Indirect calorimetry was used to measure substrate oxidation rates.
- Studies involved varying insulin and glucose concentrations in normal volunteers.
- Total glucose disposal rates were analyzed under different hormonal conditions.
Main Results:
- Glucose independently increased carbohydrate oxidation and decreased lipid oxidation.
- Insulin demonstrated a 2.4-fold greater stimulation of carbohydrate oxidation compared to glucose at matched glucose disposal rates.
- At maximal glucose disposal with suppressed free fatty acids, carbohydrate oxidation correlated with glucose disposal rate, not glucose or insulin levels.
Conclusions:
- Both glucose and insulin stimulate carbohydrate oxidation in humans.
- Carbohydrate oxidation rate is influenced by free fatty acid availability and glucose availability.
- Insulin primarily regulates free fatty acid availability, while both hormones enhance glucose availability to tissues.