Hyperpyruvaturia in experimental diabetes.

1. The 24 hourly excretion of pyruvate and glucose has been measured in alloxan-diabetic rats.2. The animals were allowed a 6-day control period before being injected with alloxan (I.V. 50 mg/kg body weight). The diabetes was treated by daily injections of insulin for a period of 6 days from the 7th to the 12th day following the alloxan injection.3. The pyruvate excretion increased more than 5-fold following the induction of diabetes, the values being 189 +/- 130 (S.D.) mug/24 hr in the control period rising to an average of 1002 +/- 664 (S.D.) mug/24 hr over the first 6 days of diabetes. The administration of insulin over the second 6-day period of diabetes caused the pyruvate excretion to decrease-though not significantly. Upon the withdrawal of the insulin treatment the pyruvate excretion increased significantly from 785 +/- 315 (S.D.) mug/24 hr to 2105 +/- 679 (S.D.) mug/24 hr, measured over a 5-day period. The final period of pyruvate excretion was significantly greater than the excretion over the first diabetic period.4. The glucose excretion during the initial diabetic period was 6.75 +/- 2.64 (S.D.) g/24 hr. The administration of insulin caused a 42% decrease in glucose excretion compared to a decrease of 22% for the pyruvate. The withdrawal of insulin caused the glucose excretion to increase by 149% while the pyruvate excretion increased by 157%.5. Diabetes was also induced temporarily by injections of anti-insulin serum and diazoxide. In each case significant glycosuria and hyperpyruvaturia were produced.6. The possible causes of the hyperpyruvaturia in diabetes are discussed.