THE METABOLISM OF THE CARBOHYDRATES 715 



may be restored sufficiently to effect a practical cure. In any case 

 "insulin" has a profound effect on carbohydrate metabolism for we have 

 found (in collaboration with Hepburn, Latchford and Noble) that it 

 causes the respiratory quotient to rise almost to unity when given along 

 with sugar to diabetic animals (and also to diabetic patients), in which 

 also it causes large amounts of glycogen to appear in the liver. Insulin 

 also greatly reduces the blood sugar in normal rabbits and in rabbits 

 showing hyperglycemia as a result of piqure, injection of adrenalin or 

 asphyxia. 



DIABETIC ACIDOSIS OR KETOSIS 



Nature and Cause. Much confusion has existed in medical literature 

 over the correct definition of acidosis, mainly because the term was first 

 used for the particular variety of the condition observed in the later 

 stages of diabetes mellitus. The acids which accumulate in the tissue 

 fluids in this disease are acetoacetic and /3-oxybutyric, which are re- 

 lated to acetone and are derived from fatty acids by a faulty metabolism 

 (see page 737). The essential cause of the acidosis is therefore en- 

 tirely different from that in nephritis; in diabetes foreign acids are 

 added to the blood, whereas in nephritis the acids of a normal metab- 

 olism accumulate because of faulty excretion through the kidneys. 

 The usual signs of acidosis exist in both cases, because the surplus of 

 acid depletes the store of bicarbonate and causes changes in the alveolar 

 C0 2 , in the C0 2 -absorbing power of the blood, in the reserve alkalinity, 

 and in the acid excretion by the kidney. It is important to recognize the 

 special nature of diabetic acidosis by a separate name ketosis. 



The chemical processes by which the kQtone bodies are produced are 

 discussed elsewhere (page 737). It remains for us to consider the 

 general nature of the metabolic disturbance responsible for the appear- 

 ance of ketone bodies in diabetes. 



For the thorough combustion of fat in the animal body a certain 

 amount of carbohydrate must be simultaneously burned. Fat evidently 

 is a less readily oxidized foodstuff than sugar; it needs the fire of the 

 burning sugar to consume it. If the carbohydrate fires do not burn 

 briskly enough, the fat is incompletely consumed; it smokes, as it were, 

 and the smoke is represented in metabolism by the ketones and derived 

 acids. Such a closing down of the carbohydrate furnaces may be 

 brought about either by curtailment 4 of the intake of carbohydrates, as 

 in starvation (page 600), or by some fault in the mechanism of the 

 furnace itself, as in diabetes. Besides fat, protein may also contribute 

 to the production of ketones when carbohydrate combustion is de- 



