A subject when fasting completely, possesses no residual carbohydrates after the fifth or sixth day (we know this from animal experiments and from a study of the respiratory quotient). The daily carbohydrate catabolism cannot very well be greater than would correspond to the metabolism of nitrogenous material. The nitrogen metabolism may fall as low as 8 to 9 grm. a day, and about 40 grm. of sugar that are formed from distintegrating body proteids correspond to this amount of nitrogen. Such a fasting individual never excretes more than 20 grm. of acetone - bodies a day (calculated for acetone). On the other hand, there are numerous cases of diabetes - and we, ourselves, have a number of such examples on record, - in which the conditions are as follows: if they live on a strict diet containing much proteid they excrete no sugar. The daily nitrogen metabolism amounts to 25 to 30 grm. The amount of proteid sugar that corresponds to this amount of nitrogen and that is formed and later disintegrated in the organism, is three times as great as the amount one would calculate in a fasting subject. In addition there are at least ten to fifteen grm. of carbohydrate that are ingested with the food, even on a very strict diet. Nevertheless, we often find an excretion of from 40 to 50 grm. of acetone bodies, calculated for acetone, whereas in reality we should have expected less than in a fasting subject, provided the quantity of destroyed carbohydrate and not certain peculiarities of the diabetic organism determined the excretion of acetone.

It has already been mentioned above that a healthy subject living on a mixed diet containing a sufficient quantity of proteids and fats and at least 80 grm. of carbohydrates does not develop acetonuria. In diabetic subjects, on the other hand, we occasionally encounter cases that disintegrate at least 110 and even 150 grm. of carbohydrates and still excrete acetone, or in which at least the excretion of acetone is only slightly influenced by the addition of this large quantity of carbohydrates to the diet. Cases of the latter kind, it is true, are comparatively rare.