title: Effects of hyperglycemia on glucose metabolism before and after oral glucose ingestion in normal men.
abstract: The plasma glucose excursion may influence the metabolic responses after oral glucose ingestion. Although previous studies addressed the effects of hyperglycemia in conditions of hyperinsulinemia, it has not been evaluated whether the route of glucose administration (oral vs. intravenous) plays a role. Our aim was to determine the effects of moderately controlled hyperglycemia on glucose metabolism before and after oral glucose ingestion. Eight normal men underwent two oral glucose clamps at 6 and 10 mmol/l plasma glucose. Glucose turnover and cycling rates were measured by infusion of [2H7]glucose. The oral glucose load was labeled by D-[6,6-2H2]glucose to monitor exogenous glucose appearance, and respiratory exchanges were measured by indirect calorimetry. Sixty percent of the oral glucose load appeared in the systemic circulation during both the 6 and 10 mmol/l plasma glucose tests, although less endogenous glucose appeared during the 10 mmol/l tests before glucose ingestion (P < 0.05). This inhibitory effect of hyperglycemia was not detectable after oral glucose ingestion, although glucose utilization was increased (+28%, P < 0.05) due to increased nonoxidative glucose disposal [10 vs. 6 mmol/l: +20%, not significant (NS) before oral glucose ingestion; +40%, P < 0.05 after oral glucose ingestion]. Glucose cycling rates were increased by hyperglycemia (+13% before oral glucose ingestion, P < 0.001; +31% after oral glucose ingestion, P < 0.05) and oral glucose ingestion during both the 6 (+10%, P < 0.05) and 10 mmol/l (+26%, P < 0.005) tests. A moderate hyperglycemia inhibits endogenous glucose production and contributes to glucose tolerance by enhancing nonoxidative glucose disposal. Hyperglycemia and oral glucose ingestion both stimulate glucose cycling.
authors.affiliation: Service de Nutrition-Diabétologie, Hôpital Haut-Lévêque, Ave. de Magellan, 33600 Pessac, France. vincent.rigalleau@wanadoo.fr
authors.forename: Vincent
authors.initials: V
authors.lastname: Rigalleau
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Beauvieux
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Gallis
authors.forename: Henri
authors.initials: H
authors.lastname: Gin
authors.forename: Phillippe
authors.initials: P
authors.lastname: Schneiter
authors.forename: Luc
authors.initials: L
authors.lastname: Tappy
mesh_terms: D000284:Administration, Oral; D001786:Blood Glucose / Q000378:metabolism*; D002096:C-Peptide / Q000097:blood; D005934:Glucagon / Q000097:blood; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D006943:Hyperglycemia / Q000378:metabolism*; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D005934:Glucagon; D005947:Glucose