Submitted to: Journal of Pediatric Endocrinology & Metabolism
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/25/2007
Publication Date: 1/21/2008
Citation: Toffolo, G., Man, C.D., Cobelli, C., Sunehag, A.L. 2008. Glucose fluxes during OGTT in adolescents assessed by a stable isotope triple tracer method. Journal of Pediatric Endocrinology & Metabolism. 21(1):31-45. Interpretive Summary: The aim of this study was to determine glucose kinetics during a glucose meal. We used three glucose compounds labeled with non-radioactive stable isotopes "triple tracer method". Two were given intravenously and one via the glucose meal. Using this technique, we demonstrated that about 10% of the ingested glucose was extracted by the liver; the body's own production was suppressed by 45%, and the peripheral uptake of glucose was increased by 21%. We conclude that this method provided accurate measures of the inflow and uptake of glucose and the suppression of the body's own production of glucose during a glucose meal. Thus, the study provided new insights on postprandial glucose metabolism in adolescents. Further, this method will be useful in future studies to investigate meal-related glucose metabolism under various pathological conditions in lean and obese adolescents.
Technical Abstract: Virtually no information is available on glucose fluxes during a meal or glucose ingestion in adolescents. Our study was designed to use a triple tracer approach to measure rates of appearance of ingested glucose (Raogtt), endogenous glucose production (EGP), and glucose disappearance (Rd) following an oral glucose bolus in adolescents. Eleven adolescents (4 M/7 F, 15 +/- 1 yr; 67.3 +/- 4.7 kg; 24 +/-2 kg/m2) underwent a frequent sampled oral glucose tolerance test (OGTT) (labelled with [6,6-2H2]glucose) combined with intravenous infusion of [1-(13)C]glucose and [U-(13)C6]glucose following an overnight fast. Formulas were developed to estimate glucose fluxes using one- or two-compartment models. During the 7 h following the OGTT bolus, 9.8 +/- 2.3% of the ingested glucose was extracted by the liver, EGP was suppressed by 45 +/- 4% and Rd increased by 21 +/- 5%. The triple tracer method provided accurate assessment of Raogtt, EGP, and Rd fluxes during an OGTT in adolescents. Thus, this method might provide novel insight on postprandial glucose fluxes in children/adolescents under various conditions.