680 METABOLISM 



similar to removal of more of the gland, or, on the other, conditions 

 which might prevent the incidence of diabetes, even though this extra 

 portion of pancreas is removed. 



From the work which he has already done, Allen believes that he has 

 sufficient evidence to show that the continued feeding with excess of 

 carbohydrate food will surely convert a mild into a severe case, and in 

 one experiment he succeeded in bringing about the same transition by 

 performing puncture of the medulla that is, by creating an irritative 

 nervous lesion. By none of the other means usually employed to produce 

 experimental glycosuria could the bordering case be made diabetic, 

 although one such animal became acutely diabetic after ligature of the 

 portal vein. To the clinical worker the value of these results lies in the 

 fact that they furnish experimental proof that a so-called latent case 

 of diabetes that is, one that has a low tolerance value for carbohy- 

 drates may be prevented from developing into a severe case by proper 

 control of the diet. Attempts to show whether or not there are any 

 conditions which might bring about improvements in animals that were 

 just diabetic have not as yet been sufficiently made to warrant any con- 

 clusions that could help us in the treatment of human cases. The en- 

 couragement of the internal pancreatic secretion by diminution of that 

 discharge into the intestine may be of value. 



The certainty with which diabetes results from pancreatectomy in dogs, 

 as well as the frequent occurrence of demonstrable lesions in the pan- 

 creas in diabetes'in man, leaves no doubt that this gland must be in some 

 way essential in the physiologic breakdown of carbohydrates in the 

 normal animal, but how, we can not at present tell. All we know is 

 that the first change to occur after the gland is removed, is a sweeping 

 out of all but a trace of the glycogen of the liver, although the muscles may 

 retain theirs ; indeed, in the cardiac muscle there may be more than 

 the usual amount. 28 Nor can any glycogen be stored in the liver when 

 excess of carbohydrates is fed. After the glycogen has disappeared, 

 gluconeogenesis sets in, so that the tissues come to melt away into sugar, 

 and all the symptoms of acute starvation, associated with certain others 

 that are possibly due to a toxic action of the excess of sugar or other 

 abnormal products in the blood, make their appearance. 



So far it might be permissible to consider an overproduction of glu- 

 cose as the cause of the hyperglycemia of pancreatic diabetes, just as 

 we have seen it to be of these forms of hyperglycemia that are due to 

 stimulation of the nervous system ; but this can not be the case, for 

 another very definite abnormality in metabolism becomes evident 

 namely, an inability of the tissues to burn sugar. This fact is ascer- 

 tained by observing the respiratory quotient. When glucose is added 



