328 C-PEPETIDE EXCERTION DURING THERAPY OF DIABETIC KETOACIDOSIS

Measurement of serum and urine C-peptide (CPR) have been used to demonstrate residual insulin producing capacity in diabetes. The duration and dynamics of residual β-cell function have not been thoroughly investigated. Sequential measurement of serum and urine CPR were made during and after therapy for ketoacidosis in a 15 year old boy with JODM of 10 months duration. Serum CPR ranged from 0.3-0.6 ng/ml, approaching the lowest levels detectable by RIA. Urine C-peptide excretion increased over the 5 days of observation. Urinary clearance and fractional excretion (CC-peptide/Ccreat.) of C-peptide also increased 6-10 fold. Despite low serum CPR, these data are compatible with increased endogenous insulin production during therapy for ketoacidosis. Changes in renal blood flow or tubular disposition of C-peptide may have contributed to the progressive increase in urine C-peptide excretion.