title: Soluble transferrin receptor and risk of type 2 diabetes in the obese and nonobese.
abstract: BACKGROUND
  Studies evaluating the relationship between soluble transferrin receptor (sTfR), a biomarker inversely related to body iron stores, and risk of type 2 diabetes mellitus (T2DM) are scarce and inconclusive. Furthermore, sTfR concentrations have been observed to be significantly higher in obese than in nonobese individuals. Therefore, the aim of this study was to assess the relationship between sTfR and the risk of T2DM in obese and nonobese subjects.
  
  
  METHODS
  A nested case-control study of 153 cases of newly diagnosed diabetic subjects, 73 obese and 80 nonobese, and 306 individually matched controls, 138 obese and 166 nonobese, who did not develop T2DM for a median 6-year follow-up (interquartile range: 3·9-6·5) was conducted using data from the PREvention with MEDiterranean Diet (PREDIMED) cohort (http://www.controlled-trials.com/ISRCTN35739639). Cases and controls were matched for age (≤ 67 vs. > 67 years), gender, dietary intervention group and BMI (≤ 27 vs. > 27 kg/m2).
  
  
  RESULTS
  Waist circumference is the main determinant of sTfR concentrations in the whole sample (β = 0·476, P < 0·001), in the obese (β = 0·802, P < 0·001) and the nonobese (β = 0·455, P = 0·003). Furthermore, sTfR is directly associated with the risk of T2DM in obese individuals (OR = 2·79; 95% CI: 1·35-5·77, P = 0·005) and inversely associated in nonobese individuals (OR = 0·40; 95% CI: 0·20-0·79, P = 0·015).
  
  
  CONCLUSIONS
  The association between sTfR levels and risk of T2DM in a population at high cardiovascular risk depend on the presence or absence of obesity. While in nonobese subjects elevated sTfR levels are associated with a decreased risk of developing T2DM, in obese subjects the risk increases. This suggests that obesity alters the relationship between sTfR and T2DM incidence.
authors.affiliation: Nutrition and Public Health Unit, Faculty of Medicine and Health Sciences, Universitat Rovira i Virgili, Reus, Spain.|Department of Nutrition and Dietetics, Faculty of Health Sciences, University of Atacama, Copiapó, Chile.
authors.forename: José C
authors.initials: JC
authors.lastname: Fernández-Cao
authors.affiliation: Nutrition and Public Health Unit, Faculty of Medicine and Health Sciences, Universitat Rovira i Virgili, Reus, Spain.|Reus-Altebrat Primary Care, Institut d'Investigació en Atenció Primària (IDIAP), Jordi Gol i Gurina, Reus, Spain.|Pere i Virgili, Health Research Institute (IISPV), Universitat Rovira i Virgili, Reus, Spain.
authors.forename: Victoria
authors.initials: V
authors.lastname: Arija
authors.affiliation: Nutrition and Public Health Unit, Faculty of Medicine and Health Sciences, Universitat Rovira i Virgili, Reus, Spain.|Pere i Virgili, Health Research Institute (IISPV), Universitat Rovira i Virgili, Reus, Spain.
authors.forename: Núria
authors.initials: N
authors.lastname: Aranda
authors.affiliation: Reus-Altebrat Primary Care, Institut d'Investigació en Atenció Primària (IDIAP), Jordi Gol i Gurina, Reus, Spain.|Pere i Virgili, Health Research Institute (IISPV), Universitat Rovira i Virgili, Reus, Spain.|Human Nutrition Unit, Faculty of Medicine and Health Sciences, Universitat Rovira i Virgili, Reus, Spain.|CIBERobn Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain.
authors.forename: Josep
authors.initials: J
authors.lastname: Basora
authors.affiliation: CIBERobn Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain.|Primary Health Care Centre of Tafalla, Servicio Navarro de Salud-Osasunbidea, Navarra, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Diez-Espino
authors.affiliation: CIBERobn Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain.|Department of Internal Medicine, Hospital Clínic, Institut d'Investigació Biomédica August Pi I Sunyer (IDIBAPS), University of Barcelona, Barcelona, Spain.
authors.forename: Ramón
authors.initials: R
authors.lastname: Estruch
authors.affiliation: CIBERobn Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain.|Cardiovascular Risk and Nutrition Research Group, Municipal Institute for Medical Research (IMIM-Hospital del Mar), Barcelona, Spain.
authors.forename: Montse
authors.initials: M
authors.lastname: Fitó
authors.affiliation: CIBERobn Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain.|Department of Preventive Medicine and Public Health, School of Medicine, University of Valencia, Valencia, Spain.
authors.forename: Dolores
authors.initials: D
authors.lastname: Corella
authors.affiliation: Pere i Virgili, Health Research Institute (IISPV), Universitat Rovira i Virgili, Reus, Spain.|Human Nutrition Unit, Faculty of Medicine and Health Sciences, Universitat Rovira i Virgili, Reus, Spain.|CIBERobn Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Salas-Salvadó
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000453:epidemiology* / Q000209:etiology; D038441:Diet, Mediterranean; D005260:Female; D006801:Humans; D007501:Iron / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D011990:Receptors, Transferrin / Q000097:blood*; D012307:Risk Factors
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D011990:Receptors, Transferrin; D007501:Iron
keywords: 
  PREDIMED
  ; Body iron stores; nested case-control; obesity; soluble transferrin receptor; type 2 diabetes mellitus