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

Diabetologia. 2007 Sep;50(9):1930-1937. doi: 10.1007/s00125-007-0743-8. Epub 2007 Jul 18.

Abstract

Aims/hypothesis: 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/interpretation: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adiponectin / blood
  • Aged
  • Blotting, Western
  • Coronary Disease / blood
  • Diabetes Mellitus, Type 2 / blood*
  • Diabetic Angiopathies / blood
  • Humans
  • Insulin / blood
  • Lipoproteins / blood
  • Male
  • Metabolic Syndrome / blood*
  • Middle Aged
  • Reference Values
  • Retinol-Binding Proteins, Plasma / metabolism*

Substances

  • Adiponectin
  • Insulin
  • Lipoproteins
  • RBP4 protein, human
  • Retinol-Binding Proteins, Plasma