title: Measurement of cerebral oxidative glucose consumption in patients with type 1 diabetes mellitus and hypoglycemia unawareness using (13)C nuclear magnetic resonance spectroscopy.
abstract: The aim of the present study was to use (13)C nuclear magnetic resonance (NMR) to measure the cerebral oxidative metabolic rate of glucose (CMRglc[ox]) in patients with diabetes and to compare these measurements with those collected from matched controls. We elected to study a group with type 1 diabetes mellitus and hypoglycemia unawareness because we had previously found such patients to have higher brain glucose concentrations than healthy volunteers under steady-state conditions. We sought to determine if this difference in steady-state brain concentrations could be explained by a difference in CMRglc(ox). Time courses of (13)C label incorporation in brain amino acids were measured in occipital cortex during infusion of [1-(13)C]glucose. These time courses were fitted using a 1-compartment metabolic model to determine CMRglc(ox). Our results show that the tricarboxylic acid cycle (TCA) cycle rate (V(TCA), which is twice CMRglc[ox]) in subjects with type 1 diabetes mellitus was not significantly different from that of healthy controls (0.84 +/- 0.03 vs 0.79 +/- 0.03 micromol/[g min], n = 5 in each group, mean +/- SEM). We conclude that the changes in steady-state brain glucose concentrations that we observed in patients with type 1 diabetes mellitus in a previous study (J Neurosci Res. 2005;79:42-47) cannot be explained by changes in oxidative glucose consumption.
authors.affiliation: Department of Radiology, University of Minnesota Medical School, Minneapolis, MN 55455, USA. henry@cmrr.umn.edu
authors.forename: Pierre-Gilles
authors.initials: PG
authors.lastname: Henry
authors.forename: Amy B
authors.initials: AB
authors.lastname: Criego
authors.forename: Anjali
authors.initials: A
authors.lastname: Kumar
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Seaquist
mesh_terms: D000328:Adult; D001364:Awareness; D001921:Brain / Q000378:metabolism*; D002247:Carbon Isotopes; D016022:Case-Control Studies; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007003:Hypoglycemia / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008875:Middle Aged; D008962:Models, Theoretical
chemical_list: D002247:Carbon Isotopes; D005947:Glucose