Urinary C-peptide as a measure of beta-cell function after a mixed meal in healthy subjects: comparison of four-hour urine C-peptide with serum insulin and plasma C-peptide.
Urinary C-peptide (UCP) is a noninvasive measure of integrated insulin production, and the usefulness of 24-h collections has been previously reported. Only small numbers of subjects have been studied using shorter urine collections. To see how well 4-h urine collections for C-peptide (UCP) correlate with serum immunoreactive insulin (SI) and plasma C-peptide (PCP), we studied 41 healthy subjects (19 men, 22 women) using as a stimulus a 600-kcal mixed meal and the same mixed meal after oral prednisone. UCP values correlated best with the area under the curves for SI (r = 0.457, P less than 0.001) and PCP (r = 0.557, P less than 0.001). UCP was also significantly correlated with peak SI (r = 0.382, P less than 0.001), peak PCP (r = 0.496, P less than 0.001), fasting SI (r = 0.297, P = 0.007), and fasting PCP (r = 0.341, P = 0.007) values. Urinary C-peptide was significantly correlated with SI and PCP concentrations in a broad range of physiologic values for SI and PCP supporting the usefulness of UCP as a simple, noninvasive measure of beta-cell function. Four-hour collections for UCP may be useful in further studies of beta-cell function.
D000293:Adolescent; D000328:Adult; D000368:Aged; D002096:C-Peptide / Q000097:blood / Q000652:urine*; D004435:Eating; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood*; D007515:Islets of Langerhans / Q000378:metabolism*; D007668:Kidney / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011241:Prednisone / Q000494:pharmacology; D013997:Time Factors
D002096:C-Peptide; D007328:Insulin; D011241:Prednisone