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. ) μg/24 hr in the control period rising to an average of 1002 ± 664 ( S.D. ) μg/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. ) μg/24 hr to 2105 ± 679 ( S.D. ) μg/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.