title: Quantitative metabolomics by H-NMR and LC-MS/MS confirms altered metabolic pathways in diabetes.
abstract: Insulin is as a major postprandial hormone with profound effects on carbohydrate, fat, and protein metabolism. In the absence of exogenous insulin, patients with type 1 diabetes exhibit a variety of metabolic abnormalities including hyperglycemia, glycosurea, accelerated ketogenesis, and muscle wasting due to increased proteolysis. We analyzed plasma from type 1 diabetic (T1D) humans during insulin treatment (I+) and acute insulin deprivation (I-) and non-diabetic participants (ND) by (1)H nuclear magnetic resonance spectroscopy and liquid chromatography-tandem mass spectrometry. The aim was to determine if this combination of analytical methods could provide information on metabolic pathways known to be altered by insulin deficiency. Multivariate statistics differentiated proton spectra from I- and I+ based on several derived plasma metabolites that were elevated during insulin deprivation (lactate, acetate, allantoin, ketones). Mass spectrometry revealed significant perturbations in levels of plasma amino acids and amino acid metabolites during insulin deprivation. Further analysis of metabolite levels measured by the two analytical techniques indicates several known metabolic pathways that are perturbed in T1D (I-) (protein synthesis and breakdown, gluconeogenesis, ketogenesis, amino acid oxidation, mitochondrial bioenergetics, and oxidative stress). This work demonstrates the promise of combining multiple analytical methods with advanced statistical methods in quantitative metabolomics research, which we have applied to the clinical situation of acute insulin deprivation in T1D to reflect the numerous metabolic pathways known to be affected by insulin deficiency.
authors.affiliation: Endocrinology Research Unit, Division of Endocrinology, Mayo Clinic College of Medicine, Rochester, Minnesota, United States of America.
authors.forename: Ian R
authors.initials: IR
authors.lastname: Lanza
authors.forename: Shucha
authors.initials: S
authors.lastname: Zhang
authors.forename: Lawrence E
authors.initials: LE
authors.lastname: Ward
authors.forename: Helen
authors.initials: H
authors.lastname: Karakelides
authors.forename: Daniel
authors.initials: D
authors.lastname: Raftery
authors.forename: K Sreekumaran
authors.initials: KS
authors.lastname: Nair
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000378:metabolism; D001798:Blood Proteins / Q000378:metabolism; D002853:Chromatography, Liquid; D003920:Diabetes Mellitus / Q000097:blood / Q000188:drug therapy / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000627:therapeutic use; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D053858:Metabolic Networks and Pathways; D055432:Metabolomics; D015999:Multivariate Analysis; D025341:Principal Component Analysis
chemical_list: D000596:Amino Acids; D001798:Blood Proteins; D007328:Insulin; D005947:Glucose