Use of urinary C-peptide to estimate insulin secretion during starvation.
The usefulness of measurements of urinary C-peptide excretion in indirectly assessing integrated insulin secretion during starvation was studied in eight obese subjects during a 72-h fast. Blood and urine samples were collected at 12-h intervals for measurement of insulin and C-peptide immunoreactivity. After 60 h, serum insulin and plasma C-peptide levels declined 47% and 37%, respectively, and the values were highly correlated (r = 0.8; P less than 0.001). By 72 h, urinary C-peptide excretion had declined to 70% of the level in the first 12-h period. The urinary clearance of C-peptide was not altered by starvation. A highly significant correlation was found between urinary C-peptide and C-peptide secretory rate (P less than 0.001). The molar ratio of plasma C-peptide to insulin remained constant during the fasting period. These data indicate that basal insulin secretion can be added to the list of physiological conditions in which beta-cell secretion can be effectively evaluated by urinary C-peptide measurement.
D000328:Adult; D002096:C-Peptide / Q000097:blood / Q000652:urine*; D003404:Creatinine / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D000078790:Insulin Secretion; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D012636:Secretory Rate; D013217:Starvation / Q000378:metabolism / Q000652:urine*
D002096:C-Peptide; D007328:Insulin; D003404:Creatinine