Gerhardt, who in 1865 discovered the fact that the addition of perchloride of iron to the urine of certain diabetes pro duced a red color, thought that it was due to the diacetic ether which decom poses readily' in acetone, CO„ and alco hol. Von Jaksch attributes this colora tion to the diacetic acid; but the fact that the injection of considerable doses of this substance does not give rise to symptoms resembling those of diabetic coma leads one to doubt that the acci dents of diabetic coma are solely due to its presence.
Boussingault formerly found as much as 1.6 grammes of ammonia per litre of diabetic urine; this enormous daily ex cretion of ammonia appeared incredible, and Koppe argued against the exactitude of Boussingault's method; but in 1880, Hallerworder fully confirmed the results of Boussingault, basing his observations upon the researches of Walter, made cording to the directions of Schmiede berg.
[These researches proved the fact that where a mineral acid penetrates into the blood ammonia is formed in the econ omy, by neutralization; R. LEPINE.] Hallerworder did not hesitate to affirm that in diabetic subjects there exists an excess of acid, perhaps lactic acid. Sta delmanni by treating all the acids and all the bases in the urine as had been done by Goethgens, found that, while in the normal urine the known acids exceed the bases, the contrary is the case in betic urine, and that consequently there must exist in the latter some unknown acid. As a matter of fact, from several litres of diabetic urine Stadelmann suc ceeded in directly extracting crotonic acid, and Minkowski, continuing his re searches, proved that the crotonic acid does not pre-exist in the urine, but that it is a product of the decomposition of oxybutyric acid. At the same time Kitlz, in view of the fact that the urine of some diabetics deviates strongly to the left after the fermentation of the sugar, discovered, on his side, that this deviation is due to a substance of a com position identical with that of the known oxybutyric acids, but differing from the latter through the property of deviating to the left. Deichmfiller, Zyrnanski and
Tollens, Lepine and Hugounenq, and others have confirmed the existence of oxybutyric acid in the urine of certain diabetics.
In twenty-one cases of diabetic coma all patients eliminated large quantities of acid; but a comatose condition may be due to increased destruction of nitrog enous material in other maladies, and administration of alkalies is without effect; hence, coma is not due to acid intoxication. As means of restricting nitrogenous destruction, S ounces of fat daily; milk or levulose if disgust occur. Klemperer (Mtinch. med. Woch., May 14, '95).
The most probable cause of diabetic coma is the formation and retention in the organism of the decomposition-prod ucts of sugar, such as acetone, diacetic a.cid, and more especially of beta-oxy butyric acid. These acids have fre quently been found both in the blood and in the urine of patients suffering from diabetic coma. Among the pre disposing causes of coma, age ranks as an important one, this complication of dia betes being especially frequent between 20 and 40 years of age. Among other causes, Cassoute notes an exclusively meat diet and many agents, such as opium, which tend to restrain and di minish the glycosuria. Cassoute (Gaz. des 110p., '96).
According to our present knowledge, it may be definitely stated that diabetic coma is due to an acid intoxication pro duced by the circulation of excessive quantities of beta-oxybutyric, and pos sibly also diacetic, acid in the blood, these being the products of the decom position of the body-albumins. Thomas B. Futcher (.N. Y. Med. Jour., vol. lxvi, No. 25, p. S21, '97).
It is generally admitted that acetone arises from the decomposition of oxy butyric acid, according to the following equations:—