198 ^^WOOGICAL CHEMISTRY 



tion and>aruses glycosuria. This form of glycosuria depends 

 upon TOe rapidity of absorption, hence it is most easily 

 produced when the carbohydrate is given in the form of 

 glucose. If given in the form of starch the carbohydrate 

 must be hydrolysed before absorption, hence the concentration 

 of sugar in the intestine depends on the rate of hydrolysis 

 and the sugar is absorbed as it is formed. The absorption of 

 sugar is therefore slower and the liver can deal with it 

 better, thus a larger quantity of carbohydrate can be given 

 in the form of starch than of glucose, without producing 

 glycosuria. Maltose, lactose and cane-sugar, if injected into 

 the blood, are excreted unchanged in the urine, but if 

 given by the mouth they must be hydrolysed. In normal 

 individuals it is found that alimentary glycosuria can be 

 produced by more than about 150-180 g. of glucose. 



120-150 g. of fructose. 

 20 g. of galactose. 

 120 g. of lactose. 

 150-200 g. of cane-sugar.* 



If glycosuria is produced by less amounts than these the 

 sugar " tolerance " is said to be decreased. The measurement 

 of sugar tolerance is frequently performed as an indication of 

 an individual's liability to diabetes. 



The limits for alimentary glycosuria are not absolute, but 

 they serve as a general indication of the ability of the individual 

 to absorb and store carbohydrate. 



Phloridzin Glycosuria. Administration of the glucoside 

 phloridzin produces glycosuria. This is not due to the sugar 

 in the glucoside as the decomposition product, phloretin, 

 produces a similar but weaker result. It is stated that the 

 amount of sugar in the blood is not increased, and that this 

 form of glycosuria differs from other forms in that the 

 permeability of the kidney for sugar is increased.! 



This form of glycosuria is largely used for experimental 

 purposes to show what substances can be converted into 

 glucose by the animal body (p. 107). Phloridzin, suspended 

 in olive oil, is injected and the dose repeated until the excretion 

 of sugar is uniform. This sugar is mainly formed from protein, 



as the ratio of glucose to nitrogen in the urine ( N ratio J is 



the same as the ratio of the total amount of carbon when 

 converted into sugar to the nitrogen in protein. Some 



* C. von Norden, Die Zitckerkrawkheit, 5th edition, 1910, p. 21. 

 f I. v. Mering, Zeit. f. klin. Med., 1888, vol. 14, p. 405. 



