242 FORMATION OF SUGAR FROM FAT 



Respiratory Quotient in Diabetes. Attempts have also 

 been made to prove that sugar is produced from fat from 

 a study of the ratio of the respiratory quotient in diabetes. 

 It is well known that the respiratory quotient, the ratio 

 between the output of C0 2 and the intake of oxygen, when 

 combustion of carbohydrates alone is in process, is 

 ^?=i, because the different sugars contain H and in 

 the proportions of water and necessarily no oxygen is 

 needed to oxidize the hydrogen into water. But as this is 

 involved to a marked degree when fat (very poor in oxygen) 

 is burned, the respiratory quotient falls to 0.7 in the actual 

 consumption of fat. The portion of oxygen intake which 

 is employed in the oxidation of H into water of course does 

 not appear as C0 2 . In the combustion of protein the 

 quotient is about 0.8. What may be expected, however, if in 

 a diabetic there takes place transformation of higher fatty 

 acids into sugar and this be excreted as such? As there 

 must of necessity be a number of CH 2 complexes reformed 

 into CH.OH., a considerable amount of oxygen will be re- 

 quired ; and, as the new-formed sugar is not consumed but 

 is excreted, the intake of oxygen cannot at all coincide with 

 the C0 2 output. It is evident, therefore, that a marked 

 lowering of the respiratory quotient must manifest itself. 

 Magnus-Levy has calculated that the respiratory quotient 

 will of necessity fall to 0.6 or lower under such conditions ; 

 but even in diabetes of severe type he found an actually 

 higher proportion, while Pfliiger, taking the same observa- 

 tions as his basis but other methods of calculation, actually 

 obtained in the case of a severe diabetic a quotient of almost 

 exactly 0.6, and believed that this proved beyond doubt 

 that fat is a source of sugar. 58 Unfortunately it must be 

 acknowledged that the elements, which have been basically 

 assumed for calculation, are not as yet established with the 



58 A. Magnus-Levy, Verhandl. d. physiol. Ges. Berlin, March 1, 1904; 

 Centralbl. f. Physiol., 18, 373, 1904; Zeitschr. f. klin. Med., 56, 83, 1905; 

 consult therein the Literature. E. Piiiiger, Pfluger's Arch., 108, 473, 1905. 



