Observations on the mechanisms of glucosuria during glucose loads in normal and nondiabetic subjects.

The study of 14 normal young men by glucose titration procedures has defined the magnitude of splay in this population, differing from previously reported data in its unexpected deviation from the line of theoretic unity high on the titration curve. Compared to these normal subjects, a group of glucosuric men could be divided into two subclasses, those with normal maximal rate of glucose reabsorption (Tm(G)) and those with subnormal Tm(G), both with comparably abnormal splay. Most consistent glucosurics fall into the latter group. Nephritic patients studied were not such a homogeneous group in terms of age and sex, but did manifest an abnormal splay during their titration curves in most cases. They also demonstrated a greater than normal reabsorptive rate of glucose per unit measured glomerular filtration rate. It is concluded that renal glucosuria must be defined not only in terms of the concept of Tm(G) but also by deviation of the glucose titration curve expressing an unusual degree of splay. The latter is presumed, as has been suggested by others, to be a characteristic of nonhomogeneity of glucose handling units in the kidney. This seems subject to exaggeration in the adaptations which accompany chronic renal disease.