920 NUTRITION AND HEAT REGULATION. 



fatal disease the amount of sugar lost daily in the urine may be very 

 large. In severe forms of the disease practically all the carbohydrate 

 of the food may be excreted in the urine in the form of sugar, 

 and even when the carbohydrate in the diet is eliminated com- 

 pletely, sugar continues to be secreted in the urine in consider- 

 able amounts. In these latter cases the sugar is supposed usually to 

 have its source in the proteins of the food or of the body, a view 

 which is supported by the fact that the amount of nitrogen and 

 dextrose excreted in the urine exhibit a constant relation to each 

 other. The ratio of dextrose to nitrogen (D : N) in a carbohydrate- 

 free diet is given as 3.65 to 1.* If the amount of protein in the diet 

 is increased there is an increased elimination of sugar as well as 

 nitrogen in the urine, the proportion of 3.65 grams of dextrose to 

 1 gram of nitrogen remaining practically unchanged. The obvious 

 explanation of this constant relationship is that the sugar is formed 

 from the protein, and it may be estimated (Lusk) on the basis of 

 the ratio 3.65 to 1 that 58 per cent, of the metabolized protein is 

 converted to sugar. In pancreatic diabetes in dogs a lower ratio 

 of 2.8 to 1 is reported. The general and specific symptoms ob- 

 served in diabetes mellitus closely resemble those observed upon 

 dogs suffering from pancreatic diabetes. It seems probable, there- 

 fore, that in man the condition of diabetes may also be due in the 

 first place to some trouble in the pancreas which prevents it from 

 giving off its normal internal secretion. Whether or not the activity 

 of the pancreas is impaired in all these cases, the majority of those 

 who have studied the subject agree that the final difficulty lies 

 in the fact that the tissues, especially the muscular tissues, can- 

 not utilize the sugar brought to them by the blood, f Assuming the 

 correctness of the usual view, it has been a question as to what part 

 of the process of glycolysis is affected. This process it will be re- 

 membered is supposed to comprise two general stages, a series of 

 preparatory non-oxidative changes and a terminal series of oxida- 

 tions yielding CO 2 and H 2 O. Corresponding to this general point 

 of view, some authors have supposed that in the diabetic individual 

 the activity of the enzymes responsible for the preparatory changes 

 is at fault, while others have supported the opposite theory. At 

 present experiments on dogs exhibiting pancreatic diabetes seem to 

 favor the view that it is the second stage that is interfered with. | 

 In addition to the sugar found in the urine in diabetes, this secre- 

 tion may also contain considerable amounts of the acetone bodies, 

 namely, /3-oxy butyric acid, aceto-acetic acid, and acetone. It 



* Lusk, "Elements of the Science of Nutrition," Philadelphia, 3d ed., 1917. 



fFor literature on the Metabolism of Diabetes, see Lusk, "Archives of 

 Internal Medicine," Feb., 1909; Magnus-Levy, "The Medical Record," Dec. 

 3, 1910, and Minkowski, ibid., Feb. 1, 1913. 



t Verzar, " Biochemische Zeitschrift," 66, 75, 1914. 



