Renal clearance, insulin secretion and glucose tolerance in spontaneous diabetes mellitus of dogs.

A standard intravenous glucose tolerance test (IVGTT) and the insulin response to the glucose loads were studied in 14 cases of diabetes mellitus in dogs. In addition, urinary glucose excretion, and clearances of urea, creatinine and phosphate were also determined in these dogs. All diabetic dogs were characterized by glucose intolerance as expressed by an abnormal half-time (T 1/2) or fractional clearance rate (k-value) and were further classified as Types I, II or III diabetes on the basis of their insulin responses. Renal functional impairment was observed in about 60 percent of the cases and was generally mild. There appeared to be no apparent relationship between advanced chronic renal disease and severity of diabetes in dogs.

Renal function, insulin secretion, and glucose tolerance in mild streptozotocin diabetes in the dog.

A mild, stable diabetes mellitus was induced in dogs, using a small (20 mg/kg of body weight) dose of streptozotocin in a standard volume of 200 ml infused in 15 minutes. The stability of the diabetes was evidenced by the results of a standard intravenous glucose-tolerance test, insulin response to the glucose load, and urinary glucose excretion. The results of the urinary clearances for urea, creatinine, and phosphate indicated minimal renal toxicosis and that the toxicosis was localized to the tubules.

The effect of urinary glucose excretion on the plasma glucose clearances and plasma insulin responses to intravenous glucose loads in unanaesthesized dogs.

The effect of urinary glucose excretion on the plasma glucose clearance and insulin response to varying sizes of glucose loads was studied in normal unanaesthesized dogs. Glucose loads ranging from 0.15 to 1.25 g/kg b.w. were infused intravenously in a standard time period of 30 seconds. Plasma glucose and plasma immunoreactive insulin (IRI) concentrations were determined during one-hour after infusion. All urine excreted during the one-hour was collected by a catheterization and bladder wash-out procedure. The urinary glucose excretion was expressed as the percent of the glucose load. The urinary glucose excretion varied directly with the size of the glucose load and ranged from minimal to 12%. This would indicate that urinary losses play a considerable role proportionate to the degree of hyperglycaemia above the renal threshold. Thus, urinary loss of glucose must be recognized as an important factor infuencing the plasma glucose clearance and hence the plasma IRI response. A glucose load of 0.5 g/kg b.w. given in 30 seconds with the k-value calculated between 15-45 min would minimize the influence of urinary loss and provide more accurate plasma clearance values.