To determine the effects of different hypocaloric diets on insulin secretion, 24-h urine C-peptide was measured in 11 obese subjects on a weight-maintaining baseline diet, and the results were compared with values obtained during 14-day periods of diets containing 400 kcal/day of only protein (n = 6) or glucose (n = 5), followed by 14 days of fasting and 14 days of refeeding on 800-1000 kcal/day. A significant positive correlation between total caloric intake and urine C-peptide excretion was found once the C-peptide excretion reached steady state after several days on each diet. Multiple regression analysis showed no contribution of body weight to urine C-peptide during the different diets. In contrast, a significant correlation was found between body weight and urine C-peptide in the fasting state. A marked and identical decrease of ∼75% in urine C-peptide occurred over the first 5-7 days of the two 400-kcal diets, followed by a further decrease during fasting to 5% of baseline values. Refeeding was associated with a progressive increase. Plasma insulin and C-peptide followed the same trends as found for urine C-peptide, although the magnitude of change was much smaller. C-peptide clearance was not assessed because of the variation in plasma levels on eating meals. However, the same responses were found when C-peptide excretion was factored for creatinine excretion. Thus, the major determinant of urine C-peptide excretion appears to be food intake, and adaptations take 5-7 days to reach steady state. This probably accounts for the significant correlation between body mass and urine C-peptide seen only afterfasting, when the effect of ingested secretagogues is removed. Glucose andprotein appear to be equipotent insulin secretagogues in the hypocaloric diets studied.
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Original Contribution|
April 01 1987
Urine C-Peptide As Index of Integrated Insulin Secretion in Hypocalpric States in Obese Human Subjects
Jean-François Yale;
Jean-François Yale
McGill Nutrition and Food Science Centre
Montreal
, and the Departments of Medicine and Nutritional Sciences, University of Toronto
Toronto, Canada
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Lawrence A Leiter;
Lawrence A Leiter
McGill Nutrition and Food Science Centre
Montreal
, and the Departments of Medicine and Nutritional Sciences, University of Toronto
Toronto, Canada
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Errol B Marliss
Errol B Marliss
McGill Nutrition and Food Science Centre
Montreal
, and the Departments of Medicine and Nutritional Sciences, University of Toronto
Toronto, Canada
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Address correspondence and reprint requests to Dr. Errol B. Marliss, McGill Nutrition & Food Science Centre, Royal Victoria Hospital, Room H6.90, 687 Pine Avenue West, Montreal, Quebec H3A 1A1, Canada.
Current address of L.A.L. is University of Toronto, Department of Medicine, Toronto Western Medical Building, 25 Leonard Avenue, Suite 410, Toronto, Ontario M5T 2R2, Canada.
Diabetes 1987;36(4):447–453
Article history
Received:
January 27 1986
Accepted:
October 23 1986
PubMed:
3545945
Citation
Jean-François Yale, Lawrence A Leiter, Errol B Marliss; Urine C-Peptide As Index of Integrated Insulin Secretion in Hypocalpric States in Obese Human Subjects. Diabetes 1 April 1987; 36 (4): 447–453. https://doi.org/10.2337/diab.36.4.447
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