DIABETES MELLITUS is a morbid condition in which the body is unable to metabolize sugars efficiently. It is this condition which is commonly termed "diabetes" (see METABOLIC DISEASES), and it is believed that it is produced when there is insufficient available insulin (q.v.) in the body. The first sug gestion that the pancreas is necessary for the complete utilization of carbohydrates in the animal body was made by Brunner in 1682. The relationship of the pancreas to diabetes was first sug gested in 1788 by Cowley, an English physician. In 1889 von Mering and Minkowski showed that the complete removal of the pancreas from animals resulted in a condition which is prac tically identical with diabetes mellitus in man. Although attempts were made to secure an anti-diabetic substance from the pancreas by scores of investigators, this substance was not proven to be present until 1921 (see INSULIN) .
Diabetes is a common disease more prevalent in towns and especially modern city life than in primitive rustic communities and frequently occurs in Jews. In the United States it is said that it affects 1% of the population. No age is exempt but most sufferers are 50-6o years. Males are affected twice as frequently as females and fair more often than dark people, while obese individuals more often suffer from diabetes than those of normal weight.
Symptoms.—The untreated diabetic patient suffers from ex treme thirst, hunger, loss of weight and strength. He excretes abnormally large quantities of urine of high specific gravity (I •o3o-1 •05o) . He is very susceptible to infection and this con dition, when established, is difficult to eliminate. The diabetic is unable to burn sugar. This sugar accumulates in the blood and is excreted in the urine. Not only are the sugars imperfectly metabolized, the fats are also not utilized in a normal manner and certain products of their abnormal or incomplete decom position accumulate in the blood and produce the conditions of acidosis and coma.
The diabetic condition is suspected when a patient complains of one or more of the symptoms or signs mentioned above. An analysis of the urine for sugar should always be made. Diabetes may be present and sugar may be found in the urine when the patient is not aware of any of these symptoms. The routine analysis of the urine in life insurance examinations has resulted in the early diagnosis of many cases of diabetes. The prognosis of the early case is, of course, much better than the advanced case since treatment can be instituted earlier in the disease. The amount of sugar in the blood, under certain standard conditions, is a valuable indication of the severity of the disease. The pres ence in the urine of the acetone bodies formed from the abnormal breakdown of fats is a warning that acidosis or coma is imminent. The presence of these substances in the body can sometimes be suspected by the characteristic odour which they impart to the breath.
By evaporation crystals of sugar may be obtained from dia betic urine, which also yields the characteristic chemical tests of sugar. The quantity of sugar passed daily may vary from a few ounces to two or more pounds, and is markedly increased after saccharine or starchy food has been taken. Sugar may also be found in the blood, saliva, tears, and in almost all the excre tions.
Diabetes as a rule advances comparatively slowly except in the young, in whom its progress is often rapid. The complications of the disease are many and serious. It may cause impaired vision by weakening the muscles of accommodation, or by lessen ing the sensitiveness of the retina to light. Also cataract is very common. Skin affections of all kinds may occur and prove very intractable. Boils, carbuncles, cellulitis and gangrene are all apt to occur as life advances. Diabetics are especially liable to phthisis and pneumonia, and gangrene of the lungs may set in if the patient survives the crisis in the latter disease. Digestive troubles, kidney diseases and heart failure due to fatty heart are all of common occurrence. But the most serious complica tion of all is diabetic coma, which is very commonly the final cause of death. The onset is often insidious, but may be indi cated by loss of appetite, a rapid fall in the quantity of both urine and sugar, and by either constipation or diarrhoea. More rarely there is most acute abdominal pain. At first the condition is rather that of collapse than true coma, though later the patient is absolutely comatose. The patient suffers from a peculiar kind of dyspnoea, and the breath and skin have a sweet ethereal odour. The condition may last from twenty-four hours to three days only very rarely longer, but is almost invariably the precursor of death.
Treatment.—Patients suffering from diabetes mellitus are treated by dietetic measures, and if the condition is severe, by the administration of insulin. Before the discovery of insulin the methods of treatment introduced by Allen and Joslin of drastic restrictions in diet prolonged the lives of many severe diabetics.
Several important principles underlie the dietetic treatment of this disease. The diet must supply sufficient calories to the patient in order that his weight may be kept constant at the proper level. Protein, preferably as lean meat, eggs or milk, must not be reduced below a certain minimum value. If this substance is unduly reduced, the tissue protein of the patient's body is utilized. The carbohydrates and fats of the diet must be in a certain fixed proportion to each other. If the fats are present in excess of this proportion, there is danger of the production of the poisonous acetone bodies. In calculating the sugar in a diet, it is necessary to remember that sugar is formed from protein and to a lesser extent from fat, as well as from the carbohydrate of the diet. The diabetic patient is given as much sugar-forming food as he can utilize. Sugar in excess of what is utilized is excreted in the urine. The amount of excess sugar can therefore be determined by analysis.
Dietetic Measures.—The diabetic diet should consist as far as possible of easily available seasonable foods along the line of a normal diet. It is much more satisfactory for the patient to obtain the essentials of his diet from among these natural foods than to be dependent upon specially prepared diabetic foods. The diabetic diet need not be monotonous.
Mild cases of diabetes can be successfully treated by dietetic measures. If a patient excretes sugar on a diet which is sufficient only for his needs insulin must be supplied. The amount neces sary is proportional to the severity of the disease. Insulin, which is distributed as a sterile, watery solution, is administered hypo dermically. It is not effective when given by mouth. Insulin is usually administered twice a day, 15 to 3o minutes before break fast and again before the evening meal. Some patients require only one dose per day, while in very severe cases three doses are necessary.
If the diabetic patient is using a diet which is too high in fats or too low in sugar, coma may develop. A large percentage of diabetics died of coma before insulin was discovered. The treat ment of coma was to put the patient to bed, to supply fluids and alkalis, heat and stimulants and to give sugar by mouth or into a vein. These measures are still necessary. Insulin has proved a specific drug in the treatment of this condition and, when administered sufficiently early, and in large doses, the results have been very successful.
Insulin is a very powerful drug. A very serious condition may be produced by the administration of an overdose. This may be avoided on the physician's part by a very careful balancing of diet against dosage of insulin employed, and on the patient's part by a close and intelligent observance of the diet, together with a thorough understanding of the premonitory symptoms of a beginning hypoglycaemic reaction. These symptoms of slight hypoglycaemia are sudden hunger, fatigue, a peculiar restlessness of ten described by the patient as a feeling of "inward trem bling," pallor or flushing of the face, and an increased pulse rate which is a valuable sign in children. If the overdose of insulin is large and corrective measures are not taken, the patient may show profuse perspiration, tremor, emotional disturbances, col lapse and unconsciousness. The treatment of mild degrees of hypoglycaemia consists of the administration of carbohydrate in any convenient form, such as sugar candy. Should the more serious symptoms develop, orange juice with sugar added, or corn syrup, may be given by mouth. In the very severe cases, sterile dextrose is given intravenously.
In the past, less than 2o% of patients suffering from severe diabetes lived more than i o years. Children, who usually have the disease in a severe form, seldom lived for more than 6 years. The diabetes which develops in individuals over 5o years of age is usually mild and the patients may live their allotted span of years. It is not possible to state definitely as yet the exact effect of insulin on diabetic mortality. It is certain, however, that thousands are now alive who would have died had it not been for insulin. In some cases it appears that patients need less insulin than they required when treatment with the material was commenced. In the great majority of cases, however, the insulin requirement has not been markedly reduced. The severe diabetic receiving insulin is now able to live practically a normal life, but the insulin treatment cannot be discontinued.
(C. H. B.)