192 INTERMEDIATE METABOLISM 



istration of fats. On the other hand, in some cases of 

 diabetes when there is no carbohydrate in the diet the 

 D.N. ratio is higher than can be accounted for by the pro- 

 duction of sugar from protein alone. This points to sugar 

 production from fats. Though the evidence is inconclusive, 

 it seems that sugar is produced from fat to a far less 

 extent than from protein. 



Further Metabolic Changes in Diabetes 



Notwithstanding the inabihty of the tissues to burn 

 glucose, there is in the diabetic no decrease in the total 

 metabohsm or energy production of the body. The source 

 of energy must therefore be transferred to the proteins or 

 the fats. This is further shown by the low respiratory 

 quotient. In view of the large conversion of protein into 

 glucose which we have seen to occur it is obvious that the 

 abihty of the protein to take the place of carbohydrate 

 as an energy producer is very Hmited, little being left for 

 direct oxidation. The brunt of the work therefore falls 

 upon the fats, the exalted part played by them being 

 shown in the rise in blood fat (diabetic hpsemia). There 

 soon appear in the urine the so-called acetone bodies, 

 namely, /5-hydroxy butyric acid, acetoacetic acid and 

 acetone itself. These are unquestionably derived from 

 fats. How they are produced will be described later. It 

 is sufficient here to mention that their presence in the 

 urine shows that the oxidation of fats is not complete. 

 The tissues therefore either have a diminished capacity for 

 fat combustion or are unable to cope with the increased 

 fat oxidation consequent upon the failure to use proteins 

 and carbohydrates. The accumulation of acetone bodies 

 in the blood is indeed the usual cause of death in diabetics, 

 for these substances have a toxic effect upon the nervous 

 system. To some extent the body protects itself from 

 this accumulation of acids in the blood by combining the 

 acids with ammonia, which is thus deviated from its 

 normal conversion into urea. 



