I ill \li TABOLISld OF Mil C IRBOHYDRA1 



thesia. Such observations have been made on rabbits, and a few on man 

 himself. By collecting blood from the ear veins of rabbits, it lias !• 

 found that, after giving from two to ten grams of glucose by Btomach, 

 the glucose concentration of the systemic Mood begins to rise in fit - ' 

 minutes, attaining ;i maximum in about an hour and then returning 

 tin' normal level in aboul three hours. 



Similar results have been obtained by examination of the venous blood 

 in man. After giving 100 grams of glucose by mouth, for « • x .■ 1 1 1 1 1 » 1 < • . t! 

 is commonly an increase in blood sugar amounting to from 30 to 34 

 cent of the aormal and lasting for from one to four hours. The existo 

 of lliis postprandial hyperglycemia, ;is we may call it. indicates that tin' 

 sugar-retaining powers of tin- liver and mus re not sufficiently de- 



veloped to prevent the accumulation of some of the absorbed sn-_ r ar in the 

 systemic blood. Whenever this increase exceeds a certain limit, some 

 (lie sugar begins i<> escape through tin 1 kidney into the urine, producing 

 glycosuria postprandial glycosuria. Tin' concentration to which bl< 

 sugar must rise before glycosuria occurs in the case of man is. probably 

 aboul 0.10 to 0.11 gm. percent. After damage to the kidney, ;is in nephritis, 

 or in long-standing cmm's of mild diabetes, tin- percentage may probably 

 lis.- considerably higher in the blood without evidence of glycosuria. 



Value of Bloccl Examination in Diagnosis of Diabetes. — The determina- 

 tion of the amount of ingested carbohydrate required to bring about | 

 prandial glycosuria constitutes, ;^ we have already seen, the so-called 

 assimilation limit for sugar, which is often taken as an index of the sugar- 

 metabolizing power of the organism. It is evident, however, that the time 

 of onset, and the extent and duration of post prandial hyperglycemia must 

 serve as a more certain index of the sugar-retaining power of the liver 

 and muscles; and now that a simple and rapid clinical method exists 

 I Lew is Benedicl method i \,,v the accurate determination of sugar in small 

 quantities of Mood, there is no reason why this index should not 1 

 for the detection of failing powers to metabolize carbohydrat< 



Tu no disease, probably not even in tuberculosis, is it more important 

 than iii diabetes thai an early diagnosis should he made. Thus, if we find 

 that the p.. si prandial hyperglycemia after a certain amount of carbo- 

 hydrate develops to an unusually high degree ami persists for an unusual 

 length of time, we are just died in curtailing the carbohydrate supply - 



to hold that tiles,- values down to the level they attain in normal individ 

 It is almosl certain that the earliest Bign of diabetes is an unusual defj 

 and duration of postprandial hyperglycemia. At first th( sugar 



leads to no damage and it is insufficient to cause any e\ idem -l\ cosuria, al- 

 though it is quite likely that if the urine in such individuals were coiled 

 at very frequent intervals after eating carbohydrate-rich food, glucose would 



