CARBOHYDRATES AND FATS. 823 



the diabetes is the increased percentage of sugar in the blood 

 (hypergly cemia) . This result finds its most probable explanation 

 in the view that the loss of the internal secretion of the pancreas 

 robs the tissues of their power to metabolize the sugar. 



Diabetes Mellitus. In this severe and usually 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 eliminated in the urine in the form of sugar, and even when the 

 diet contains no carbohydrate, or during complete starvation, sugar 

 continues to be secreted in the urine in considerable 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 may exhibit a constant proportion to each other. The 

 ratio of dextrose to nitrogen (D : N) is given as 3.65 to 1.* 

 Special cases have been reported, however, in which the ratio 

 exceeded these figures. The general and specific symptoms observed 

 in diabetes mellitus closely resemble those observed upon dogs 

 suffering from pancreatic diabetes. It seems probable, therefore, 

 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. In addition to the sugar found 

 in the urine in diabetes this secretion may also contain considerable 

 amounts of the acetone bodies, namely, /2-oxybutyric acid, aceto- 

 acetic acid, and acetone. It is probable that these bodies rep- 

 resent intermediary products in the metabolism of the fats of the 

 body which escape oxidation. 



Phlorhizin Diabetes. Phlorhizin is a vegetable glucoside ob- 

 tained from the roots of certain trees e. g., apple, pear. When 

 injected into an animal it causes a glycosuria which is temporary, 

 but which may be renewed by repeated injections. Examination 

 of the blood in this case reveals the fact that the percentage of 

 sugar is not increased, so that the immediate cause of the glycosuria 

 is different from that responsible for the diabetes of man or of 

 animals without the pancreas. A satisfactory explanation of the 

 action of the phlorhizin has not yet been obtained, but it would 

 seem that the drug acts in some way upon the kidney itself that 

 is, the tissues of the body are probably still able to metabolize the 

 sugar, but the blood is continually depleted of this substance 

 through the kidney ; it leaks off through the kidney faster than it 

 can be utilized by the tissues. The evidence at hand seems to indi- 

 cate that the sugar (in part at least) exists in the blood in some 

 form of colloidal combination, and that under the influence of the 

 phlorhizin the kidney breaks up this combination and eliminates 

 * Lusk, "Elements of the Science of Nutrition," Philadelphia, 1906. 



