Urinary C-peptide: a simple measure of integrated insulin production with emphasis on the effects of body size, diet, and corticosteroids.
C-Peptide is secreted from the beta-cell in equimolar quantities with insulin. Since a fraction of C-peptide is excreted in the urine, measurement of C-peptide in timed urine collections is a simple indirect measure of integrated insulin production. Normal subjects were studied to determine the effects of diet and oral prednisone on urinary C-peptide excretion. In subjects on a defined diet, there is a positive correlation of urinary C-peptide with body weight. When insulin production is increased after  oral prednisone, there is also a positive correlation with body mass index and percent ideal body weight. Prednisone increases plasma glucose, immunoreactive insulin, and serum and urinary C-peptide levels beginning 8-12 h after oral administration. This effect of prednisone is most marked in the postprandial state. Diets high in carbohydrate and protein result in significantly more insulin production, as measured by urinary C-peptide, than isocaloric diets with low protein or carbohydrate composition.
D000293:Adolescent; D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight; D002096:C-Peptide / Q000097:blood / Q000652:urine*; D004032:Diet; D004040:Dietary Carbohydrates / Q000494:pharmacology; D004044:Dietary Proteins / Q000494:pharmacology; D005260:Female; D006801:Humans; D007328:Insulin / Q000096:biosynthesis* / Q000097:blood; D008297:Male; D008875:Middle Aged; D010455:Peptides / Q000652:urine*; D011241:Prednisone / Q000494:pharmacology*
D001786:Blood Glucose; D002096:C-Peptide; D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D007328:Insulin; D010455:Peptides; D011241:Prednisone