Of recent years the dietetic treatment of diabetes has been recognized to be not quite so simple as it was thought to be formerly, inasmuch as it is now recognized that different varieties of the affection require different dietetic treatment, and that it is not sufficient simply to cut off all carbo-hydrate foods in all cases. Formerly the treatment consisted simply in restricting to as great an extent as possible the intake of carbo-hydrates. It is now recognized that at any rate in some cases it is desirable to allow carefully regulated amounts of carbo-hydrates, even where their ingestion is followed by some increase in the glycosuria, and thus it is often a matter of considerable difficulty to determine what is the most suitable dietetic treatment, especially in some of the more severe forms of the disease. Again, it is somewhat difficult to draw a hard-and-fast line between the different varieties of the malady, and especially with regard to the exact relation of certain forms of intermittent glycosuria to true diabetes.
Intermittent glycosuria is seen in a number of conditions, but the most important variety from a dietetic standpoint is that where the glycosuria occurs in relation to food, the so-called alimentary glycosuria. There are various grades of severity of this affection. In the slighter forms sugar is only present in the urine after a meal containing a large quantity of sugar as such. In others, the glycosuria is present to a moderate extent so long as any considerable quantity of carbo-hydrates is present in the food, but it disappears so soon as these are cut off. In the slighter forms of glycosuria the presence of sugar is the only abnormality in the urine. On the other hand, in the more severe forms where the glycosuria is more persistent, other abnormal substances, and more particularly acetone and diacetic acid, are also present. Three cases merge into those of more severe diabetes where the glycosuria is not only persistent and accompanied by the excretion of acetone diacetic acid and oxybutyric acid, but it is influenced far less by dietetic restrictions. To this group of cases the term composite diabetes has been applied by some, inasmuch as the glycosuria persists to some degree even when the carbo-hydrates are excluded to as great an extent as possible from the food.
It is essential from the point of view of treatment to differentiate between the different forms of diabetes and to attempt to diagnose, so far as is possible, the particular variety that is present. For this purpose observations should be made on the patient to determine whether the glycosuria is only present after the ingestion of an excessive quantity of sugar or carbo-hydrate, or whether it is present with an ordinary mixed diet such as a healthy adult is in the habit of taking, or whether it is still present after the diet has been cut down so as to exclude, either partially or entirely, carbo-hydrate food. These facts can be expressed in another way by saying that the diabetic and the glycosuric vary in their tolerance of carbo-hydrates, or in the degree to which they can metabolize carbo-hydrate food. In severe cases the organism would seem to have lost all power of metabolizing carbo-hydrates and the whole of the ingested carbo-hydrate is excreted. Further, in these cases the non-carbo-hydrate tissues of the body, especially the proteins and also the non-carbo-hydrate constituents of the food, may give rise to the formation of sugar, as such patients excrete large quantities of sugar in the urine at a time when no carbohydrate is being ingested. In this severe type of the malady protein disintegration is so great as to lead to a notable increase in the nitrogenous extractives in the urine, particularly the urea, and there is obviously a very complex disturbance of the metabolic processes.
A very important group of cases is that in which a slight trace of sugar is present in the urine from time to time, but where a test meal rich in carbo-hydrate is immediately followed by the excretion of sugar in appreciable quantity. These cases are important because usually they are discovered accidentally in the course of a routine examination, as for instance for life insurance, and although the patients may maintain a condition of good health for long periods, it would seem that a certain proportion of such cases ultimately become diabetic. This type of case is important to recognize and treat, inasmuch as they are very amenable to suitable dietetic treatment, and very commonly only slight restriction in the diet is necessary in order to lead to the disappearance of the glycosuria.
Although it is of the first importance in the dietetic treatment of diabetes for a careful examination of the urine to be made, both from the point of view of the amount of sugar present and its relation to the character of the food, and also to determine the presence or absence of such substances as acetone and diacetic acid, yet attention must not be concentrated exclusively on the urine, and the diet must not be regulated entirely by the effects produced on the urine. Thus a rigid diet may lead to a diminution in the quantity of urine and in the amount of sugar present, and the patient's symptoms, especially his thirst, may be relieved to a greater or less extent. Yet such a patient may not be improving when tested in other ways, and more especially when observations on the body-weight are made at regular intervals. A progressive loss of weight may often be observed where a rigid diet is being given, and yet where the quantity of sugar excreted has diminished as a result. In these cases, however, the serious nature of the disease can often be recognized by the presence of considerable quantities of diacetic acid and oxybutyric acid in the urine. Some amelioration in these severe cases may be often observed as the result of allowing carefully regulated quantities of carbo-hydrates in the food.