Urine C-peptide and creatinine (Jaffe method) excretion in healthy young adults on varied diets: sustained effects of varied carbohydrate, protein, and meat content.
We studied effects of isocaloric diets of varied composition (each diet offered for 5 to 7 days) on urine C-peptide and creatinine excretion in eight healthy subjects. C-peptide excretion was higher on the high carbohydrate (60% CHO, 20% PRO) and high protein (45% CHO, 30% PRO) diets than on the low carbohydrate (30% CHO, 20% PRO) and low protein diets (45% CHO, 10% PRO). C-peptide excretion correlated with total kilocalories ingested (r = 0.594, p less than 0.001), and also with CHO (r = 0.469, p = 0.003) and PRO intake (r = 0.453, p = 0.004). Multiple regression analysis is given by the formula: Urine C-peptide (nmol/24 h) = 17.3 + 0.01 (kcal/24 h) + 0.021 (gm CHO/24 h) + 0.049 (gm PRO/24 h) Creatinine excretion was related to body weight (r = 0.959, p less than 0.001) and also to total PRO intake (r = 0.569, p less than 0.001) and meat intake (r = 0.367, p less than 0.05). We conclude that diet composition, especially protein intake, is an important stimulus to sustained insulin production as measured by C-peptide in healthy subjects. Diet composition has a significant impact on creatinine excretion. Urine creatinine cannot be assumed to reflect only lean body weight when it is used as a measure of the adequacy of timed urine collections.
D000328:Adult; D000704:Analysis of Variance; D001806:Blood Urea Nitrogen; D001835:Body Weight; D002096:C-Peptide / Q000652:urine*; D003404:Creatinine / Q000097:blood / Q000378:metabolism*; D004040:Dietary Carbohydrates / Q000378:metabolism*; D004044:Dietary Proteins / Q000378:metabolism*; D002149:Energy Intake; D005260:Female; D006801:Humans; D007328:Insulin / Q000096:biosynthesis; D008297:Male; D008460:Meat; D012737:Sex Factors
D002096:C-Peptide; D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D007328:Insulin; D003404:Creatinine