The literature on the excretion of acetone in diabetes mellitus is enormous. There was much confusion in the beginning; but light was finally thrown upon this obscure subject when the factors determining the excretion of B-oxybutyric acid were elucidated and when the fact was recognized that B-oxybutyric acid, diacetic acid and acetone were derived from the same mother substance and represented merely different stages of oxydation. Whenever these acetone bodies appear in the urine, we must assume some perversion of oxydation (see above). This perversion one must imagine is greater when all the acetone bodies appear than in cases in which only acetone is excreted. Only if we consider the three acetone bodies as belonging together, and if we remember that they represent different stages of oxidation, can we credit acetonuria in diabetes with practical and theoretical significance. In other words, the excretion of the acetone bodies together in diabetes assumes the same importance that was formerly attached to diabetic acetonuria alone.

The quantity of acetone bodies excreted in diabetes varies greatly. Sometimes the quantities are so small that they barely exceed the physiological quantities that are excreted by a healthy individual living on a meat-fat diet. In other cases several grams a day are excreted. In the latter case the ferric chloride is positive. No definite numerical statements can be made in regard to the quantity of acetone that appears in cases in which diacetic acid is also excreted, nor can we determine definitely how much acetone must be present in the urine before B-oxybutyric acid appears. We can say, however, that on an average (and we know this purely empirically) 0.5 grm. of acetone must be excreted in the 24 hours before diacetic acid can be determined by the ferric chloride reaction; and again, that oxybutyric is rarely absent when more than 1.5 to 2 ctgr. of acetone are excreted per diem. On the other hand, the absence of acetone does not always indicate that oxybutyric acid is also absent. There are conditions in which the oxidative powers of the organism are damaged to such an extent that the B-oxybutyric acid that is formed cannot even be oxidized to acetone. As a matter of fact, cases with diabetic coma are on record in which no acetone was excreted and in which all of the acetone bodies appeared in the form of oxybutyric acid.

The quantity of oxybutyric acid excreted in the urine varies greatly in each individual case. Sometimes only a few grm. are excreted per diem and in other cases 30, 40 and more grm. a day may be excreted for weeks. The highest figures have been found in coma or after coma. Magnus-Levy records a daily excretion of 150 to 180 grm. of B-oxybutyric acid a day in cases of comatose diabetics. No one will seriously deny nowadays that the typical coma of diabetes is due to an autointoxication with B-oxybutyric acid and that it is the acid character of this body more than any specific toxic property that determines the syndrome of coma (see above). Quantities of oxybutyric acid have been found in the urine and in the blood that, to judge from animal experiments, must be considered lethal. In addition a number of symptoms may be mentioned that are common both to diabetic coma and experimental acid intoxication. In the first place, we have the peculiar dyspnoea, then the increased pulse rate, the lowering of the temperature, the decrease in the blood alkalescence and the increased excretion of ammonia that may amount to 10 grm. pro die. The question arises now why such large quantities of acetone bodies are formed in diabetes, quantities that by far exceed those excreted in any other form of acetonuria. In this connection we wish again to distinctly emphasize that there is no tangible evidence to demonstrate that there is an enterogenous intoxication as assumed by some authors (Schmitz, Kraus). If we review ail the conditions that determine the excretion of oxybutyric acid and of acetone in diabetes we will find that the following important facts may be considered established (von Noorden).