THE METABOLISM OF THE CARBOHYDRATES 707 



hyperglycemias must be one of our aims in the treatment of early stages 

 of the disease. 



It is possible that- the relationship of nerve strain to the incidence of 

 diabetes has been exaggerated, for it has been stated that there was a 

 marked decrease in the number of cases of this disease in Berlin during 

 the later years of the war. During this period the nerve strain was very 

 great, but the diet was greatly restricted and it may be in light of the 

 latter fact that the disease is related more to dietetic habits than to con- 

 ditions of nerve strain (Magnus Levy). In view of the observations, it 

 is significant that diabetes is said to be increasing in frequency in the 

 United States since prohibition came into effect. The excessive consump- 

 tion of sugar is possibly responsible for this condition. 



Although there can be no doubt that the glycogenic function of the 

 liver is subject to nerve control, it is probable that its control by hor- 

 mones is of equal if not greater importance. This dual control of a 

 glandular mechanism is by no means unique for the glycogenic function, 

 for we have already seen it to exist in the case of the gastric glands 

 and the pancreas, and it is probable that it also exists in the case of 

 the thyroid. It may well be that the nerve control of the glycogenic 

 function has to do only with those transitory changes in sugar produc- 

 tion that would be demanded by sudden activities of muscle, and that 

 the hormone control has to do with the more permanent process of build- 

 ing up and breaking down of glycogen to meet the general metabolic 

 requirements of the tissues. 



HORMONE CONTROL AND PERMANENT DIABETES 



Nervous excitation can explain only transitory increases in blood sugar, 

 the more permanent hyperglycemias being dependent upon some dis- 

 turbance in the hormone control of carbohydrate utilization. This dis- 

 turbance is a much more serious affair than that produced by nervous 

 excitation. In the latter case the hyperglycemia ceases whenever all 

 of the glycogen stores of the liver have been exhausted; whereas a dis- 

 turbance in the hormone control, besides causing as its first step a 

 breakdown of all the available glycogen, goes on to cause a production 

 of sugar out of protein. A process of gluconeogenesis (new formation 

 of glucose) becomes superadded on one of glycogenolysis. 



To ascertain the nature of this hormone and the mechanism of its 

 action has been the object of most of the researches on those forms of 

 diabetes that are produced by changes in certain of the ductless glands. 

 The following possibilities may be considered: (1) that the controlling 

 agency is the concentration of glucose in the blood; (2) that it is the 



