Evidence that kidney function but not type 2 diabetes determines retinol-binding protein 4 serum levels.

Abstract

OBJECTIVE:

It has been suggested that retinol-binding protein 4 (RBP4) links adiposity, insulin resistance, and type 2 diabetes. However, circulating RBP4 levels are also affected by kidney function. Therefore, the aim of this study was to test whether RBP4 serum levels are primarily associated with kidney function or type 2 diabetes.

RESEARCH DESIGN AND METHODS:

RBP4 serum concentration was determined by enzyme-linked immunosorbent assay in 126 nondiabetic and 104 type 2 diabetic subjects. The study population was divided according to estimated glomerular filtration rate (eGFR) into the following groups: eGFR >90 ml/min per 1.73 m(2) (n = 53), 60-90 ml/min per 1.73 m(2) (n = 90), 30-60 ml/min per 1.73 m(2) (n = 38), and <30 ml/min per 1.73 m(2) (n = 49). Each group was subdivided into nondiabetic and type 2 diabetic subjects.

RESULTS:

RBP4 serum concentration was elevated (2.65 vs. 2.01 micromol/l; P < 0.001) and eGFR was reduced (56 vs. 74 ml/min per 1.73 m(2); P < 0.001) in type 2 diabetic vs. nondiabetic subjects, respectively. By stratifying for eGFR, no more differences in RBP4 serum concentration were detectable between type 2 diabetic and nondiabetic subjects. A linear regression analysis revealed an influence of eGFR (r = -0.477; P < 0.001) but not A1C (r = 0.093; P = 0.185) on RBP4 serum concentration.

CONCLUSIONS:

Existing human data showing elevated RBP4 levels in type 2 diabetic patients may be the result of moderate renal insufficiency rather than support for the suggestion that RBP4 links obesity to type 2 diabetes.

• Authors: Andrea Henze, Simone K Frey, Jens Raila, Martin Tepel, Alexandra Scholze, Andreas F H Pfeiffer, Martin O Weickert, Joachim Spranger, Florian J Schweigert
• Journal: Diabetes (Diabetes) Vol. 57 Issue 12 Pg. 3323-6 (Dec 2008) ISSN: 1939-327X [Electronic] United States
• PMID: 18796616 (Publication Type: Journal Article, Multicenter Study, Research Support, Non-U.S. Gov't)

Chemical References

• Biomarkers
• RBP4 protein, human
• Retinol-Binding Proteins, Plasma

Topics

• Biomarkers (blood)
• Cohort Studies
• Diabetes Mellitus, Type 2 (blood, physiopathology)
• Diabetic Nephropathies (blood)
• Female
• Glomerular Filtration Rate
• Humans
• Insulin Resistance (physiology)
• Kidney Function Tests
• Male
• Obesity (blood)
• Reference Values
• Regression Analysis
• Retinol-Binding Proteins, Plasma (metabolism)