Von Noorden2 and Magnus-Levy3 report cases in which there was a considerable excretion of aceton bodies in the urine when carbohydrates were burned. For example, one patient eliminated 4.9 grams of β-oxybutyric acid on a day when 40 grams of starch were ingested and burned. There are great individual variations. Thus, Staubli1 reports concerning a diabetic man whose ordinary mixed diet was changed to one of meat and fat, including 50 grams of bread, the whole containing 3200 calories. After ten days of this diet, during which the sugar output remained nearly constant at 100 grams, the β-oxybutyric acid fell from 37.5 grams daily to nothing. In commenting on his results Staubli says: "The important factor which causes a more serious condition in the metabolism of a diabetic is the quantity in which carbohydrate is administered in excess of the tolerance for sugar. Damage caused by a continual overworking of the sugar-burning capacity plays a large part in the progress of the disease. The considerable withdrawal of carbohydrates from the diet, even in cases of severe diabetes with high acidosis, exerts an extraordinarily beneficial influence. This can be in part explained by the increased ability to burn sugar on account of the conservation of the body's power in this direction. The improvement in the capacity for sugar combustion exerts on its side a beneficial action on the acidosis".

1 Magnus-Levy: "Ergebnisse d. inn. Med.," 1908, i, 385.

2 von Noorden: "Pathologie des Stoffwechsels," 1907, ii, 77. 3 Magnus-Levy: "Ergebnisse d. inn. Med.," 1908, i, 404.

Turning the attention now to the character of the total metabolism, one finds that the severely diabetic patient lives at the expense of protein and fat, both of which are incompletely oxidized by his organism. It follows that the ordinary methods of computation of the respiratory quotients and of the heat value of the protein and fat metabolism must be scrutinized.

Magnus-Levy2 was the first to make calculations of this sort. Lusk3 has reviewed the subject and has published a calculation for the value of the respiratory quotient of protein when the urinary D : N ratio is 3.65:

1 Staubli: "Deutsch. Arch. f. klin. Med.," 1908, xciii, 125.

2 Magnus-Levy: "Archiv fur Physiologie," 1904, 379.

3 Lusk: "Archives of Internal Medicine," 1915, xv, 939.

Converting the ratio of weights into the ratio of volumes one finds that the diabetic R. Q. for protein is 0.632.

The following calculation shows the caloric value to the organism of 1 gram of urinary nitrogen in diabetes when the D :N is 3.65:

If large amounts of ammonia are eliminated without being synthesized to urea - which is produced by an endothermic reaction - 1 calorie per gram of such extra ammonia nitrogen may be added to the calculated heat production.

If one uses the modified figures to calculate the "nonprotein respiratory quotient" in severe diabetes, it is found that the combustion of fat is indicated. A few illustrative calculations are given below, taken from the work of Lusk and of Allen and DuBois:

The last subject eliminated 71 grams of β-oxybutyric acid on the day of the experiment. It is evident that when allowance is made in the calculations for the altered course of the metabolism of protein in diabetes, the remainder of oxidizable substance possesses approximately the respiratory quotient of fat, which is 0.707.

Theoretically speaking, the subject is more complicated. For example, if ammonia be used to neutralize β-oxybutyric acid, the carbon dioxid with which it would have united to form urea will be eliminated in the respiration and tend to raise the respiratory quotient.

Magnus-Levy has called attention to a possible reduction in the respiratory quotient when β-oxybutyric acid is formed from fat. He estimates that the maximal quantity of β-oxybutyric acid derivable from 100 grams of fat is 36 grams. Under these circumstances, the respiratory quotient for fat would be reduced from 0.707 to 0.669. The case is not so simple, however, for if the 36 grams of acid formed neutralized sodium bicarbonate, 15.23 grams of carbon dioxid would be eliminated.

These relations are shown in the following table:

Theoretic Respiratory Quotient With β-Oxybutyric Acid Formed From Fat

Since other bases than sodium bicarbonate may be used for the neutralization of β-oxybutyric acid, it is apparent that the exact determination of the theoretic respiratory quotient when this acid is produced in large amounts in human diabetes is at present impossible.

The establishment of the diabetic quotient at the level of 0.69 also throws light on the dogma regarding the conversion of fat into sugar. Pembrey1 calculated that if olein were in large part converted into glucose the respiratory quotient for the reaction would be 0.281. The actual findings of the respiration measurements carry the refutation of the idea that fat may be converted into sugar.

It may be well to insert a warning against the too literal interpretation of respiratory quotients obtained under grossly abnormal circumstances. This may be illustrated by the experiments of Porges and Salomon,2 who ligated the abdominal aorta and the inferior vena cava just below the diaphragm in depancreatized dogs, thereby cutting off the blood-supply to the abdominal organs and probably eliminating half the normal quantity of blood from the circulation. Under these circumstances the respiratory quotient rose to unity and the authors concluded that the diabetic organism could oxidize glucose. This doctrine was refuted by Murlin, Edelmann, and Kramer,1 who showed that the high respiratory quotient was merely incident to the elimination of carbon dioxid from the blood itself.

1 Pembrey: "Journal of Physiology'," 1901-02, xxvii, 71.

2 Porges and Salomon: "Biochemische Zeitschrift," 1910, xxvii, 143.