The relative proportions of fermentable and non-fermentable reducing substances of hyperglycaemic bloods of diabetics without glycosuria.

CLAUDE BERNARD first showed that sugar is a normal constituent of blood and recognised that glycosuria is, in some manner, dependent upon hyperglyeaemia. Since then a vast literature has accumulated on the subject and though the consensus of opinion favours the view that there is a renal threshold for sugar this view is not, as yet, unanimous. Thus, according to Benedict et al. [1918], urine normally contains glucose which is excreted continuously, the process being termed glycuresis. On the other hand, Folin and Berglund [1922] claimed that in the absence of emotional complications ingestion of as much as 200 g. of glucose did not cause the appearance of sugar in the urine of normal persons and concluded that glycuresis represents absorption and excretion of foreign unusable carbohydrate materials present in the ingested food. More recently, however, Hassan [1928] was able to prepare glucosazone from many samples of normal urine and concluded that failure to detect glucose in the past was due to technical difficulties. The writer repeated Hassan's work and obtained somewhat similar results (unpublished data). In quite an exhaustive study, on the other hand, Harding and Selby [1931] concluded that within the limits of analytical methods, fermentable sugar is absent from normal fasting urine. Analysis of all of the data; however, shows that Hassan's results, those of Harding and Selby and our own are not incompatible with each other. Thus, Hassan's data, as well as our own, clearly indicate that though normal urine may have contained glucose, detection of this sugar depended upon the time elapsing between collection of the urine and the last meal; as the fasting state was approached, the urine contained less and less sugar. This agrees with the findings of Harding and Selby who observed that, though there was no glycosuria in the fasting state, 50 % of medical students showed small amounts of fermentable sugar in the postprandial afternoon urine. The finding of sugar in normal urine appears at first to be incompatible with the renal threshold concept. Experiences with blood-sugar-time curves, however, suggest otherwise. Frank [1913] first made the observation that