The low renal threshold for glucose in diabetics

This paper deals with the results of the intramuscular insulin injection in 22 cases of diabetes and 10 normal subjects.After insulin injection the blood and urine samples for glucose determination were collected every 30 minutes for 2 hours.As a result of comparing the concentrations of glucose in the blood with those in the urines,the renal threshold for glucose could be obtained. It was found that one third of the diabetics definately had low renal threshold for glucose,but none of the normal subjects did.The lowest value of mean renal threshold for glucose in the diabetics was 59 mg/dl.Therefore,if urine sugar is used as the index to evaluate the severity of the disease,it is very important to know whether the urine sugar properly reflects the blood glucose level or not first.The low renal threshold for glucose in these diabetics did not show any relation to the types,the course and the degree of control of the disease or to inheritance.No definite diabetic nephropathy has been found in this group of patients.We believe that the damage of proximal convaluted tubules caused by hyperglycemia might be the underlying mechanism of this phenomenon.