670 DIABETES 



However, such animals are not free of glycogen. If they are sub- 

 jected to some treatment which has a strong glycogen mobilizing effect 

 the glycosuria may be made to rise temporarilj^, just as though the 

 dog had been given a dose of sugar. Thus, exposure to cold sufficient 

 to cause shivering, the administration of epinephrine, or an ether or 

 nitrous oxide narcosis, injection of acid (and various other toxic sub- 

 stances capable of producing tissue asphyxia and acidosis), all may 

 increase the urinary glucose without increasing the nitrogen, and 

 thus cause an increased G : N ratio. But if the exposure to cold is 

 long and intense enough a time comes when it ceases to have this effect, 

 and if epinephrine is given subcutaneously in the dosage of about 0.4 

 mg. per kg. of body weight once every three hours there is for a time 

 a heavy increase of the glucose output, but this becomes less and less 

 until after 6 or 8 doses the ratio becomes constant again, regardless of 

 whether epinephrine is given or not. In such dogs neither cold nor 

 narcosis nor other toxic effects will increase the output of glucose, 

 and analyses of the liver and muscles reveal no glycogen. In a long 

 series of dogs so treated Sansum and the writer have not encountered 

 ratios above 3.2 to 1, and the 2.8 ratio recurs frequently. 



Since the glycogen is gone and the dog is fasting, the sugar which 

 continues to appear in the urine must have its origin in body fat or 

 protein, or both. 



Sugar from Fat. — If such, a dog be given large quantities of fat 

 in the diet no change occurs in the G : N ratio, nor any increase in 

 the glycosuria, except such as may be ascribed to the glycerol of the 

 fat (Lusk). On the other hand, propionic acid, according to Ringer, 

 may cause a rise in the sugar excretion and a corresponding rise in the 

 G : N ratio. "^^ From this it is concluded that the fats of the food do not 

 as a rule form sugar in the body, although sugar formation from at 

 least one lower fatty acid is possible in view of Ringer's experiment. 



Von Noorden and Falta and their associates have regarded sugar 

 formation from fat as a regular normal phenomenon, because in dia- 

 betes melitus they believe that high ratios occur which make this view 

 necessary. 



Sugar from Protein.— If instead of fat, protein be given to the 

 dog above mentioned, there occurs an absolute rise in the sugar of 

 the urine and a corresponding rise in the nitrogen, bid the G : N ratio 

 remains constant. Following a meat feeding there may be fluctuations 

 of the ratio during short periods, but this statement generally holds 

 if the time of observation is 12 to 24 hours. These facts have led Lusk 

 to the conclusion that when in a fasting, fully phlorhizinized animal, 

 or one fed on meat and fat alone, a constant G : N ratio of 3.0") : 1 

 is seen; this means that the glucose and the nitrogen arc coming from 

 one and the same source, viz., protein. A gram of nitrogen corresponds 



■" The dogs used liy Ringer were not free of glycogen and possibly the extra 

 sugar did not arise from the acid given. 



