Another general principle applicable to all cases of diabetes is that changes in the diet in either direction should be made gradually. There would seem to be some risk of the production of diabetic coma, so-called acetonemia, as a result of sudden changes in diet in either direction. Instances of the occurrence of diabetic coma have been known as the result of suddenly putting a patient on an extremely rigid diet, and it is also well known that indulgence in forbidden articles of diet has also been followed by the development of this fatal complication. Although the diabetic is unable to metabolize most forms of carbo-hydrate, this disability is not equally marked with all carbo-hydrates, and lactose and laevulose are less harmful than dextrose. Laevulose is more easily assimilated than lactose, the main objection to its administration in diabetes is the difficulty in obtaining it pure, and it is expensive; but appreciable quantities can be given to many diabetics without its administration being followed by any increase in the glycosuria. Although the diabetic cannot usually metabolize carbo-hydrate material, it is of some interest that if pyrexia occurs as the result of some intercurrent illness complicating diabetes, the excretion of sugar in such a case may undergo a great diminution. This may be seen where diabetes is complicated by even such a prolonged febrile illness as enteric fever, and it would seem that during the pyrexial process the altered metabolism is capable of oxidizing sugar.
Where The Restricted Diet Leads To The Disappearance Of Sugar From The Urine , as in the well-known so-called alimentary type of the disease, the restricted diet should be maintained for prolonged periods, and when the urine has remained free from sugar for some months, small quantities of carbo-hydrate, such as 2 oz. of bread, may be allowed daily. The urine should be tested to see if it remains free from sugar, and if it does the quantities of carbo-hydrate allowed should be gradually increased, the amount given being determined by the effect on the urine. In many of these cases it has been found that as a result of the withholding of carbo-hydrate food for some time the patient has subsequently been able to metabolize at any rate moderate quantities of carbo-hydrates without the development of any glycosuria. The dietetic treatment of these cases presents no great difficulty, although special ways of cooking the food are often necessary, at any rate in the earlier stages of the treatment inasmuch as flour and other carbo-hydrate materials are so constantly used in the cooking of a very large number of articles of diet, e.g. soups, meat, fish and vegetables. The amount of carbo-hydrate allowed in the form of bread or potatoes in this type of case is entirely determined by the effect on the urine.
In The Second Type Of Case, Where The Greatest Restriction In The Diet Leads Only To A Diminution In The Quantity Of Sugar Excreted , there is considerable difficulty in the successful dietetic treatment of the malady. It is especially in this type of case that harm may be done by adhering too strictly to a carbo-hydrate free diet, and the degree to which carbo-hydrates are allowed must be determined not so much by the amount of sugar present in the urine as by other considerations, such as the general condition of the patient, the state of the body-weight, and the presence or absence of considerable quantities of diacetic acid and oxybutyric acid in the urine. Further, in this type of case the sugar is derived partly from the abnormal metabolism of proteins, and hence it is. not advisable to unduly increase, as is so often done, the amount of protein in the diet. In this type of case the patient should be given a diet containing a moderate quantity of meat, fish, and eggs, together with liberal allowance of green vegetables and some bread substitute such as casoid bread. The subsequent course of the case should determine whether carbo-hydrates should be allowed or not. If, as is often the case, the sugar excretion does not fall materially and the patient begins to lose weight progressively, a definite quantity of carbo-hydrate food in the form of bread or potatoes should be ordered. Although in this way the amount of sugar excreted daily may be somewhat increased, the general condition of the patient may improve and the body-weight increase, and further, the quantity of acetone and diacetic acid in the urine undergo diminution.
There is some difference of opinion with reference to the kind of carbo-hydrate that may be given in these cases. Some authorities give definite quantities of ordinary bread, others advise oatmeal, others potatoes. It is not probable that the differences observed with these different carbo-hydrates are due to any inherent differences in the starch, but rather that they depend on the actual quantities of carbo-hydrate in any given quantity of the food-stuff. Thus, roughly, bread contains three times as much carbo-hydrate as potatoes, and hence the patient's desire for carbo-hydrate food can often be more easily satisfied with potato than with bread.
In this type of diabetic, where the excretion of sugar is not prevented but only diminished by a rigid diet, the quantities of carbo-hydrate given must be strictly moderate and kept under supervision.
It is not sufficient for the successful dietetic treatment of these cases to carefully limit or exclude, as the case may be, carbohydrate food, but it is most important to encourage as much as possible the taking of fatty food. To supply the energy that is required in the absence of carbo-hydrates, fat should be given to as great an extent as possible in the form of butter, cream, and oil. Considerable quantities of butter may be taken with vegetables and, speaking generally, vegetables that are ordered in cases of diabetes should be cooked with butter or served with butter. Considerable quantities of fat may be also given in the form of salad oil.
The Third Type Of Case Where The Rigid Diet Leads To But Little Diminution In The Sugar Excreted is a most severe form of the affection, and is that seen more especially in early life. In these cases but little benefit is obtained by rigid dieting, and the treatment should be very similar to that advocated in the second type of case, that is to say, carbo-hydrates may be allowed, the amount given being determined by the state of the nutrition, the body-weight, and the extent to which diacetic acid and similar products are present in the urine. It is especially in this type of case that much harm may be done by sudden changes in the diet, and there can be no question that a rigid diet, if persisted in, may lead to the development of acetonaemia and coma.
In some cases of diabetes renal lesions are present, more especially chronic nephritis and granular kidney. It is difficult to lay down any rules for the dieting of such cases, as with the exception of the glycosuria seen in some forms of arterio-sclerosis, all such cases are of very great severity and but little influenced by treatment. Still, it is usually impossible where renal lesions are present, to diet the patient according to the rules suitable for uncomplicated diabetes, inasmuch as the large quantities of protein suitable for the diabetic are very unsuitable for the treatment of the renal complications. As a rule these cases will require dieting rather from the point of view of the renal lesion than from the mere diabetic standpoint.