The most common form of this disease is called diabetes mel-litus, so called because the urine contains sugar, but not all cases of sugar in the urine or glycosuria should be classified as diabetes, because an excessive ingestion of carbohydrates, particularly of sugar, is likely to be followed by the appearance of sugar in the urine. This form of glycosuria is called alimentary glycosuria, and will disappear as soon as the diet returns to the normal, to reappear only when there is a repetition of the excessive use of carbohydrates in the diet.

But diabetes is a serious and incurable disturbance of the nutrition, consisting in an inability of the system to utilize sugar. As set forth in preceding chapters, all carbohydrates are reduced to monosaccharid conditions before they are absorbed. In this condition they circulate in the blood, passing to the liver through the portal vein. In the liver they are deposited in the form of glycogen, thus retiring them temporarily from the circulation. Experiment has shown that this general process of the utilization of carbohydrates in the body is largely controlled by an internal secretion from the pancreas. Experimental interference with the pancreas will interrupt or interfere with the oxidation of sugar in the body and cause it to appear in the urine. It is, therefore, believed that diabetes mellitus has for its principal cause or associated condition a disturbance of the action of the pancreas. While the glycosuria is the principal symptom, it is not the principal matter of importance. This place must be accorded to the general condition of the body - a moderate amount of sugar in the urine being of secondary importance if the general condition is good. Diabetes has been subdivided, on the basis of its severity, into mild, moderate, and severe.

The mild cases of diabetes are those in which the amount of sugar excreted is moderate in quantity and readily held under control through control of the diet. The severe forms of diabetes are those which cannot be completely controlled, even through the most rigid control of the diet. This latter form of diabetes is observed chiefly in the young. The reason for this is evident; it being an incurable disease, when it appears in the young it causes early death. When diabetes appears in those past middle age it is likely to be of the milder type.

In the treatment of diabetes it is important to accomplish the following things:

First: To maintain the general nutrition; the best index to this is the weight of the body. So long as the body weight is maintained, or, in the case of the young, the normal growth maintained, the attendants may feel assured that the general nutrition is being properly maintained.

Second: To increase the power of the body to oxidize sugar. Experiment and clinical observation have shown that, if the carbohydrates are wholly withdrawn from the diet for a time, the sugar-oxidizing function will seem to regain its power during the rest. A judicious return two or three times a year to a carbohydrate free diet seems to have the effect of strengthening the sugar-oxidizing function rather than weakening it.

Third: Every precaution must be taken to avoid complications. The most serious complication that is likely to arise as a result of the change in diet is a condition called acidosis, characterized by the presence of acid in the blood. The appearance of such acids as acetic acid is, under normal conditions, controlled, or at least their rapid oxidation assisted by the presence of carbohydrates and carbohydrate oxidation. When these are removed from the diet, there is danger of the accumulation of acids in the blood followed by serious symptoms involving the nervous system.

The following are some of the difficulties that the dietitian must seek to overcome in his choice of the dietary for these cases: First, the difficulty of arranging a diet which represents a sufficient number of calories when the carbohydrates are wholly or largely omitted. The average individual requires about 50 calories per kilo body weight when engaged in average work, while an individual of the same average weight would require about 30 calories per kilo weight when resting. Thirty calories per kilo would mean 1,800 calories for a person weighing 132 pounds. To get 1,800 calories of energy from a carbohydrate free diet demands such a large amount of various meats, cheese, fat, eggs, and other rich diet that the patient is very likely to become so tired of these nitrogenous and fatty foods that it is difficult to prepare a menu which will be accepted with relish and appetite. Another difficulty which the dietitian experiences is the almost inordinate craving on the part of the patient for carbohydrates. In normal conditions of the nutrition the craving of the patient may be interpreted as a natural index to the character of food required, but in this case the natural craving is in the opposite direction. It is, of course, true that the system needs carbohydrates, but it is unable to use them. Their presence would only tax the digestive powers, and by the presence of excessive sugar in the blood serve to disturb the general nutrition, so that it becomes a clinical necessity to avoid any such excess. This craving may become so intense that the patient will actually attempt to get these forbidden foods and necessitate some watchfulness and care on the part of the attendants to make certain that the physician's orders regarding diet shall be followed. A further difficulty to overcome is the positive distaste for one of those foods which clinical experience shows to be an absolute necessity - namely, fat. In order to get enough nutriment it is necessary for the patient to eat large quantities of fat, but many patients have difficulty in eating any fat. Certain forms of fat are less distasteful than others and should be resorted to for most of the fat food. For example, butter and cream are generally liked and can be made the source of an important portion of the fats. Breakfast bacon, nicely browned, is relished by most people and can be utilized very largely in the diet. Egg yolk contains a large amount of fat and can be freely used. Nuts, also, particularly the butter nut, the black walnut, and the Brazil nut, contain a very large proportion of fat, and these may be freely used. By using skill and ingenuity in the choice of such foods as are rich in fat and proteins, and in the preparation of them in forms and varieties that tempt the patient's appetite, it is possible to meet all the requirements of any but the more serious cases that are really moribund from the first.