Dietary Proteins Contribute Little to Glucose Production, Even Under Optimal Gluconeogenic Conditions in Healthy Humans

  1. Claire Gaudichon1,2
  1. 1Institut National de la Recherche Agronomique, Centre de Recherche en Nutrition Humaine d'Ile-de-France, UMR914 Nutrition Physiology and Ingestive Behaviour, Paris, France
  2. 2AgroParisTech, Centre de Recherche en Nutrition Humaine d'Ile-de-France, UMR914 Nutrition Physiology and Ingestive Behaviour, Paris, France
  3. 3Institut National de la Recherche Agronomique-AgroCampus, UMR Science et Technologie du Lait et de L'œuf, Rennes, France
  4. 4Centre Hospitalier Universitaire de Nantes, Hôpital Hôtel Dieu, Pharmacie, Nantes, France
  5. 5Agence Nationale de Sécurité Sanitaire de L'alimentation, de L'environnement et du Travail, Fougères Laboratory, Fougères, France
  1. Corresponding author: Claire Gaudichon, claire.gaudichon{at}agroparistech.fr.

Abstract

Dietary proteins are believed to participate significantly in maintaining blood glucose levels, but their contribution to endogenous glucose production (EGP) remains unclear. We investigated this question using multiple stable isotopes. After overnight fasting, eight healthy volunteers received an intravenous infusion of [6,6-2H2]-glucose. Two hours later, they ingested four eggs containing 23 g of intrinsically, uniformly, and doubly [15N]-[13C]–labeled proteins. Gas exchanges, expired CO2, blood, and urine were collected over the 8 h following egg ingestion. The cumulative amount of dietary amino acids (AAs) deaminated over this 8-h period was 18.1 ± 3.5%, 17.5% of them being oxidized. The EGP remained stable for 6 h but fell thereafter, concomitantly with blood glucose levels. During the 8 h after egg ingestion, 50.4 ± 7.7 g of glucose was produced, but only 3.9 ± 0.7 g originated from dietary AA. Our results show that the total postprandial contribution of dietary AA to EGP was small in humans habituated to a diet medium-rich in proteins, even after an overnight fast and in the absence of carbohydrates from the meal. These findings question the respective roles of dietary proteins and endogenous sources in generating significant amounts of glucose in order to maintain blood glucose levels in healthy subjects.

  • Received September 3, 2012.
  • Accepted November 11, 2012.

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  1. Diabetes vol. 62 no. 5 1435-1442
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