Changes in the Respiratory Quotient after Administration of Insulin and Glucose to Human Subjects on a High and on a Low Carbohydrate Diet.

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Summary.A series of investigations has been made on the respiratory quotient after administration of large and small doses of insulin and after administration of glucose on diets rich and poor in carbohydrates.The RQ curve after administration of insulin is diphasic. During the fall in the blood sugar the RQ rises, when the fall in blood sugar ceases the RQ as a rule goes back to the initial value. It would seem, therefore, that the changes in the RQ should be viewed in relation to the blood sugar fall itself.The rise in the RQ was greater after large than after small doses of insulin. The maximum RQ is attained more rapidly after large than after small doses. These two factors are unaffected by the carbohydrate content of the diet.In the glucose experiments it is shown that the excess combustion of sugar after administration of glucose is greater the higher is the glucose tolerance curve. It appears from this that a slight reduction of the carbohydrate content of the diet does not reduce the rate of combustion of carbohydrate. The characteristic high and long glucose tolerance curve on a diet poor in carbohydrates must therefore be due to a liver effect.In the calculation of “excess amount of glucose consumed minus lost glucose” in the insulin experiments it is seen that a not inconsiderable amount of glucose not seen to be oxydized disappears from the blood. The significance of this discrepancy is discussed and the conclusion is drawn that it must at any rate in part he supposed to be due to a reduced output of glucose from the liver during the insulin effect, even though it is not at present possible to account in detail for the mechanism of this process