Experiments with champagnes, various other wines and sweetmeats, which contain great quantities of sugar, gave as a regular result perceptible sugar in the urine of many individuals. As a consequence of greater quantities being taken, an excessive glycosuria set in. Its duration depended upon the occasioning causes alone. On their removal, the quantity of sugar either returned to a minimum or entirely disappeared.
The presence of sugar in normal human urine is therefore possibly in accordance with all the above-mentioned observations. This fact must be considered a physiological axiom as regards the constituents of normal urine. The quantity of sugar contained can be increased by a condition of alimentary glycosuria. But, when there is no such artificial cause, and yet the sugar is recognizable, without the ordinary régime of life being altered, still its presence is no symptom of a pathological process going on. Even the continuation of the insignificant excretion of sugar, when it continues for many years, appears to exercise no influence over the health. But as one finds many individuals in whose urine not even the minimum quantity of sugar is discoverable, it seems not improbable that in a perfectly normal condition of the organism it is possible for many individuals completely to burn up the whole of the carbo-hydrates either taken into the organism or formed within it. Such persons, in consequence of their metabolism being normal, are able to carry out the process of combustion to the full, and their excretions are of such a nature as should represent the normal processes.
But, if this condition of the excretions cannot be attained in a given individual in the desired degree, the organism is suffering from an imperfection that occurs in a normal manner (an excretion of sugar) to a certain degree and extent, such as the physiological potentialities of a living organism permit.
In one connection only, in which it afforded me practical assistance for my observations, this question has not yet been fully elucidated. Sex had not been taken into consideration during the examination of the excretion of sugar within normal physiological bounds. Whilst I was looking through the experiments of the specialists whom I have mentioned, it struck me that most of the inquiries respecting the presence of sugar in normal urine had been made in the case of men alone, and that, so far as regarded the presence of sugar, the urine of the human female had been little observed, and never quantitatively and qualitatively compared with that of man. Nicolai Ivanoff, in his dissertation (Dorpat) on the question of glycosuria in the case of pregnant women, lying-in women, and suckling women, arrived at the following final results: “A physiological glycosuria in the case of the pregnant, or of those who are lying in, has, so far as present investigations have gone, never been established, and certainly not to the extent which Blot asserts. Sugar occurs in human urine more frequently than has been hitherto supposed, but absolutely never in constant and increased quantities in that of pregnant and lying-in women.”
If, however, it has been in many cases asserted that there was an increased quantity of sugar in the urine of pregnant and lying-in women, and that this has been proved, these statements have originated from mistaking for a previously developed sugar one which has during the experiments come into existence from the action of alkalies and acids on an extractive substance which requires further examination.
For the detection of sugar in the urine several methods exist, which are more or less sensitive.
If we mix a few cubic centimetres of urine with an equal quantity of 10 per cent. solution of caustic potash, and warm a portion of this in a test-tube, we observe that the fluid in the event of a sensible quantity of sugar being present, acquires a color varying from dark yellow to yellowish brown. We can most easily assure ourselves of this if we warm only the upper part of the fluid contained in the test-tube, whereupon the upper part of the fluid will appear darker than the rest.