METABOLISM 521 



mental and surgical procedures incidental to the removal of the pituitary 

 in whole or in part, that glycosuria frequently develops which, however, 

 gradually passes away. Subsequently it was shown that mechanical or 

 electrical stimulation of the intact posterior lobe gave rise to a similar glycosu- 

 ria provided of course there was a sufficiently large amount of glycogen in 

 the liver. This effect has been attributed to an increased discharge of the 

 internal secretion of the posterior lobe into the cerebro-spinal fluid and finally 

 into the blood, which in some way lowers the assimilation limit of the ani- 

 mal and hence leads to an elimination of sugar (see chapter on Internal 

 Secretion). 



Parathyroid Glycosuria. When the thyroids and at least three of the 

 parathyroid bodies are removed in animals, there is a disturbance of carbo- 

 hydrate metabolism, a diminished tolerance for sugar, as shown by the 

 appearance of glycosuria. A similar condition is established when three 

 parathyroids and but one thyroid are removed. It would thus appear that 

 the parathyroids rather than the thyroids have an influence, though un- 

 defined in the regulation of carbohydrate metabolism. 



The problem of the storage of sugar in the body, its release and subse- 

 quent oxidation in accordance with metabolic needs is of great interest by 

 reason of the fact that it is intimately related with that grave condition of 

 persistent glycosuria seen in man and to which has been given the term: 



Diabetes. This term has been applied to a syndrome characterized by 

 persistent hyperglycemia and glycosuria accompanied by thirst, wasting of 

 the tissues and imperfect oxidation of the fats. The sugar discharged into 

 the urine varies in amounts but continues even in the absence of all carbo- 

 hydrate food. The condition is usually permanent, enduring for months or 

 years but eventually terminating in the death of the individual. 



The cause of the disease in each instance is not always clear nor the man- 

 ner in which the storage, release or oxidation of the sugar is disturbed. 



A characteristic feature of the disease is the continuous elimination of 

 sugar even in the absence of carbohydrate food. Under these circumstances 

 there is evidence that the sugar is derived from the protein consumed or 

 from the protein of the tissues or from both. It is well known that in the 

 metabolism of protein it undergoes a cleavage into an NH 2 element and an 

 organic acid radicle. It is further known that the NH 2 element is combined 

 successively with hydrogen and carbon dioxid to form ammonium carbonate 

 which is transformed in the liver into urea; that the organic acid radical is 

 converted into sugar. It has also been determined that the dextrose yielded 

 in the metabolism of protein bears to the nitrogen yield, the ratio of 3.65 

 to i, indicating that for every 3.65 grams of sugar and every gram of nitrogen 

 6.25 grams of protein have been metabolized. In diabetes, in the absence 

 of carbohydrate from the diet, this ratio of dextrose to nitrogen in the urine, 

 expressed by the symbol D : N, has been found to exist from which the de- 

 duction is made that the origin of the sugar is to be sought for in the metab 

 lism of the proteins. . - - , 



The necessity for heat-production leads to a larger consumption of fat 

 and this in turn impairs or overtaxes the capacity of the body tissues for fat 

 oxidation and hence there arises imperfectly oxidized cleavage products such 

 as /3-oxybutyric acid, aceto-acetic acid and acetone which are finally e 

 nated in the urine thus establishing the condition of acidosis. 



