title: Retinol-binding protein 4 is associated with components of the metabolic syndrome, but not with insulin resistance, in men with type 2 diabetes or coronary artery disease.
abstract: OBJECTIVE
  Retinol-binding protein 4 (RBP4) has recently been reported to be associated with insulin resistance and the metabolic syndrome. This study tested the hypothesis that RBP4 is a marker of insulin resistance and the metabolic syndrome in patients with type 2 diabetes or coronary artery disease (CAD) or in non-diabetic control subjects without CAD.
  
  
  METHODS
  Serum RBP4 was measured in 365 men (126 with type 2 diabetes, 143 with CAD and 96 control subjects) and correlated with the homeostasis model assessment of insulin resistance index (HOMA-IR), components of the metabolic syndrome and lipoprotein metabolism. RBP4 was detected by ELISA and validated by quantitative Western blotting.
  
  
  RESULTS
  RBP4 concentrations detected by ELISA were shown to be strongly associated with the results gained in quantitative Western blots. There were no associations of RBP4 with HOMA-IR or HbA(1c) in any of the groups studied. In patients with type 2 diabetes there were significant positive correlations of RBP4 with total cholesterol, LDL-cholesterol, VLDL-cholesterol, plasma triacylglycerol and hepatic lipase activity. In patients with CAD, there were significant associations of RBP4 with VLDL-cholesterol, plasma triacylglycerol and hepatic lipase activity, while non-diabetic control subjects without CAD showed positive correlations of RBP4 with VLDL-cholesterol and plasma triacylglycerol.
  
  
  CONCLUSIONS
  RBP4 does not seem to be a valuable marker for identification of the metabolic syndrome or insulin resistance in male patients with type 2 diabetes or CAD. Independent associations of RBP4 with pro-atherogenic lipoproteins and enzymes of lipoprotein metabolism indicate a possible role of RBP4 in lipid metabolism.
authors.affiliation: Department of Nephrology, Technical University Munich, Ismaningerstr. 22, 81675, Munich, Germany. maximilian.eynatten@lrz.tum.de.|Department of Medicine I, Wuerzburg University, Wuerzburg, Germany. maximilian.eynatten@lrz.tum.de.
authors.forename: M
authors.initials: M
authors.lastname: von Eynatten
authors.affiliation: Department of Intensive Care Medicine, University of Bern (Inselspital), Bern, Switzerland.
authors.forename: P M
authors.initials: PM
authors.lastname: Lepper
authors.affiliation: Department of Nephrology, Technical University Munich, Ismaningerstr. 22, 81675, Munich, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Liu
authors.affiliation: Department of Medicine I, Wuerzburg University, Wuerzburg, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Lang
authors.affiliation: Department of Nephrology, Technical University Munich, Ismaningerstr. 22, 81675, Munich, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Baumann
authors.affiliation: Department of Medicine I and Clinical Chemistry, Heidelberg University, Heidelberg, Germany.
authors.forename: P P
authors.initials: PP
authors.lastname: Nawroth
authors.affiliation: Department of Medicine I and Clinical Chemistry, Heidelberg University, Heidelberg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Bierhaus
authors.affiliation: Department of Medicine I and Clinical Chemistry, Heidelberg University, Heidelberg, Germany.
authors.forename: K A
authors.initials: KA
authors.lastname: Dugi
authors.affiliation: Department of Nephrology, Technical University Munich, Ismaningerstr. 22, 81675, Munich, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Heemann
authors.affiliation: Department of Medicine I, Wuerzburg University, Wuerzburg, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Allolio
authors.affiliation: Department of Medicine I and Clinical Chemistry, Heidelberg University, Heidelberg, Germany.
authors.forename: P M
authors.initials: PM
authors.lastname: Humpert
mesh_terms: D052242:Adiponectin / Q000097:blood; D000368:Aged; D015153:Blotting, Western; D003327:Coronary Disease / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D003925:Diabetic Angiopathies / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood; D008074:Lipoproteins / Q000097:blood; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood*; D008875:Middle Aged; D012016:Reference Values; D054839:Retinol-Binding Proteins, Plasma / Q000378:metabolism*
chemical_list: D052242:Adiponectin; D007328:Insulin; D008074:Lipoproteins; C101326:RBP4 protein, human; D054839:Retinol-Binding Proteins, Plasma