INTERMEDIATE METABOLISM OF THE FATS 



403 



(dextrose) to the nitrogen eliminated in the diet to approach a constant 

 level. This ratio, designated usually by the symbol ^ is regarded by 

 Lusk as affording valuable indication of the severity of the diabetes, 

 for he finds that upon an exclusively fat-and-protein diet the ^ ratio 

 in the severest cases of diabetes approaches a critical value of 3.65 : 1. 

 If the sugar excreted were wholly derived from protein this would 

 mean that from 6.25 grams of protein decomposed in the tissues of 

 the diabetic, 3.65 grams, or 58 per cent, of the weight of the protein, 

 was transformed into glucose. This Lusk believes to be the maximal 

 quantity of carbohydrate which is obtainable from protein, and he 

 illustrates this by reference to the following figures: 



Maximum ratios observed in: 



According to Joslin these high ratios, which usually only precede 

 death by a brief interval, are never observed if Fats be excluded 

 from the diet, a fact which is a very striking illustration of the deter- 

 minative part played by fats in the evolution of diabetic symptoms, a 

 part, however, which has only in recent years come to be fully appre- 

 ciated, thanks to the work of Allen, Joslin, Bloor and other investi- 

 gators. 



The excretion of sugar in diabetes mellitus is not attributable to 

 loss of glycogen storage-capacity on the part of the liver, for eve a in 

 fatal cases, and after a prolonged excretion of sugar, appreciable 

 quantities of glycogen may still be found in the liver. It is naturally 

 a difficult matter to ascertain whether or not the storage capacity of 

 the liver in diabetics is fully normal, but there can be no question 

 but that the main abnormality of the carbohydrate metabolism in 

 diabetes is essentially a failure to utilize the glucose in the diet. The 

 tissues which are unable to utilize glucose are nevertheless starving 

 for it and every possible mechanism for manufacturing glucose from 

 other foodstuffs, even as we have seen, from proteins, is pressed into 

 service, but the product of these efforts is still glucose and, therefore, 

 worthless or even worse, for it is excreted from the body and involves 

 a corresponding wastage of the fuel-value of the dietary. 



The failure of the diabetic to oxidize glucose does not by any means 

 originate in a failure of oxidative powers in general. On the contrary 

 the relationship of the condition to glucose and also as we shall see, to 



