34 SCIENCE PROGRESS 



During long periods, in spite of the escape of sugar from the 

 body, life in the diabetic is continued with combustion pro- 

 cesses in full vigour. This is an aspect of affairs which lent 

 a certain strength to Pavy's position. He writes scornfully of 

 those who speak as though diabetes were due to sugar failing 

 to be burnt in the system : " Nothing can be more gratuitous, 

 unfounded and misleading. There is not a particle of evidence 

 to show that defective oxidising power exists in connexion with 

 diabetes. The real fault is a condition antecedent to the oxidising 

 operation." 



There are, indeed, many facts to suggest that sugar, when 

 normally burnt, is not burnt as sugar but that its oxidation 

 follows some previous change. 



Consider the constitution of the sugar molecule : 



H H H H 



O O 



I I I I 



HOC — C — C — C — C — CH 2 OH 



1 I I I 



o 



H H H H 



If we were to assume that the free-molecule suffers oxidation 

 in the body and were to try to decide a priori the probable 

 steps involved in its oxidation, chemical and physiological 

 considerations would alike suggest the easily oxidisable alde- 

 hyde group ( — COH) as the first point for oxidative attack. 

 A deficiency in the diabetic might then be the absence of a 

 mechanism for oxidising this aldehyde group. Experimentally, 

 indeed, it has been found that if this group in sugar be oxidised 

 to a carboxyl ( — COOH) group before it is administered to a 

 diabetic, then complete oxidation follows. 

 Gluconic acid — 



H H H H 

 O O O 



HOOC — C — C — C — C — CH 3 OH 



I I I I 



o 



H H H H 



— is completely oxidised when the oxidation of sugar fails. But 

 it is no specific failure to deal with an aldehyde group that 

 stamps the diabetic, as he can equally well oxidise the substance 

 glycuronic acid, another primary oxidation product of sugar in 



