In a previous article1 I have discussed the relation of hyperglycemia to variation in the water content of the blood and of the body tissues. It was observed that all young diabetic patients responded to hyperglycemia by a concentration of the blood and an exsiccation of the tissues, while in arteriosclerotic diabetic patients the response was simply a dilution of the blood with little or no tissue dehydration. It emphasizes the precarious condition of the young diabetic patient, for he is not only liable to acidosis and coma as a result of deranged fat metabolism but also, because of the nonvolatile acidosis that accompanies anhydremia, he is continually suffering some diminution of the alkaline reserve of his blood plasma. Thus the young diabetic patient is always potentially in a state of acidosis. On the other hand, in the absence of factors that cause acute exacerbation, the arteriosclerotic diabetic patient is