Renal disease is not the only complication of diabetes that interferes with the usual dieting necessary. Phthisis occurs frequently as a complication of diabetes, and it is not as a rule advisable to treat such cases with the rigid diet employed in ordinary diabetes.
When it is desired to restrict the input of carbo-hydrates to as great an extent as possible, the food must be limited to meat, fish, green vegetables, nuts, and some bread substitute. Almost all varieties of meat and fish are allowable, with the exception of liver, sausages and oysters. Oysters contain a considerable amount of glycogen, and are not thus desirable in cases where extreme rigidity of the diet is advisable, as for example in cases of alimentary glycosuria. The diabetic can take a great variety of green vegetables, but peas and beans are usually excluded, inasmuch as these also are much more rich in starch than the ordinary green vegetables. Most blanched vegetables should be forbidden, but celery and asparagus are allowable. Further, rhubarb, tomatoes and cucumber, contain relatively little starch, and thus may be allowed.
One of the great difficulties in the treatment of the disease with rigid diet lies in the fact that in the cooking of food so much carbo-hydrate material in the form of flour is so often used. Many meat and fish dishes are served with sauces containing very considerable quantities of starch. Meat and fish will, therefore, usually have to be roasted, boiled, grilled or baked, and in the case of fish will usually have to be served with butter. The same difficulty applies to a modified extent in the case of vegetables, and it is usually advisable to cook these in butter or to serve them with butter. Meat soups may be allowed in the treatment of the disease, but most vegetable soups are not permissible, as here again they are so frequently thickened with flour.
The diabetic is unable to partake of most fruits, as these are rich in carbo-hydrate material, but the amount of sugar in strawberries and gooseberries is very small, and the same remark applies to early oranges, so that these fruits may be taken in great moderation. The diabetic can take nuts freely, except chestnuts, and nuts form a particularly valuable article of diet in these cases, as they are rich in fatty materials.
The main difficulties in the treatment of the severe cases arise from the restriction in the taking of bread, potatoes and milk. It is probable that the small quantities of milk required by an adult in tea are not prejudicial, more especially when it is borne in mind that lactose is not such a harmful form of carbo-hydrate as dextrose, and that some diabetics can metabolise lactose. The great difficulty undoubtedly is the substitution of some article in the place of bread. A great variety of substitutes prepared from cocoanut, almond-flour, bran and casein are made by the manufacturers of diabetic articles of diet. Many of the preparations recommended as bread substitutes contain appreciable quantities of starch, and in some of them the amount may be very large. Hence it is always advisable when using a bread substitute to test it for the presence of starch and sugar. In many instances it is advisable to boil the substances with dilute sulphuric acid, neutralize with a caustic alkali, and then test for sugar with Fehling's solution. Much may be done by encouraging these patients to eat nuts as a substitute for bread with the heavier meals such as lunch and dinner, but at breakfast probably one of the bread substitutes will have to be employed. The popular idea that although bread is harmful, toast is harmless, is of course entirely erroneous, and bread should only be allowed when ordered in definite quantities for cases where it is considered desirable to allow a certain quantity of carbo-hydrate. The same remark applies to the use of potatoes. These should only be given in those cases where the food is not going to be restricted so as to exclude all carbo-hydrates. Potatoes and oatmeal are very suitable kinds of carbo-hydrates to give in certain forms of diabetes, inasmuch as it is so usual to take them with large quantities of fat, either in the form of butter with potatoes, or cream with porridge. This form of dieting, however, as already stated, is only suitable to those cases of diabetes where for the reasons given above it is not considered desirable to entirely exclude carbo-hydrates from the food, and there is no reason for thinking that either potatoes or oatmeal contain carbo-hydrates that are less prejudicial to the diabetic than bread and other carbo-hydrate foods. It is merely a question of convenience of administration and percentage amount of carbo-hydrate material present.
There is some difference of opinion with reference to the use of alcoholic drinks in the treatment of diabetes. Some authorities consider that all forms of alcohol should be forbidden. Others consider that alcohol may aid in the absorption of fat and, further, that it may to some extent replace sugar. Probably if the patient's appetite is good and the digestion efficient, there is no necessity for ordering alcohol. On the other hand, in some instances where the nutrition is poor and there may be some distaste for food, it may be advisable to order small quantities of alcohol. Malt liquors and sweet wines and liqueurs are, of course, to be avoided, as they contain considerable quantities of sugar as such. Whisky and gin are usually free from sugar and the lighter hocks, Bordeaux and Moselle wines contain very little sugar. Champagne and the stronger wines, such as port and sherries, are unsuitable.
Tea and coffee may be allowed freely, and cocoa specially prepared so as to contain but little starch is also permissible.
There are a large number of articles of food prepared in a special manner so as to be free from starch and sugar that can be obtained from the firms manufacturing diabetic articles of diet. For instance, some of these manufacturers have prepared jams and marmalade for the diabetic which may suit the taste of some patients. As a rule, by care in the selection of the food and by employing special methods of cooking, the diabetic can be provided with a variety of palatable diet.