Elevated concentrations of retinol-binding protein-4 (RBP-4) in gestational diabetes mellitus: Negative correlation with soluble vascular cell adhesion molecule-1 (sVCAM-1)

Abstract

Background. Retinol-binding protein-4 (RBP-4) may increase insulin resistance (IR) in animals, with elevated levels reported in humans with obesity and type 2 diabetes. There are, however, few data on concentrations of RBP-4 in gestational diabetes mellitus (GDM).Methods. We measured fasting serum levels of RBP-4, soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) in 50 women at 28 weeks of gestation, divided according to the results of a 50 g glucose challenge test (GCT) and a 75 g oral glucose tolerance test (OGTT): (1) controls (n = 20), normal responses to both GCT and OGTT; (2) intermediate group (IG) (n = 15): false positive GCT, but normal OGTT; and (3) GDM group (n = 15), both GCT and OGTT abnormal. IR was assessed by homeostasis model assessment (HOMA-IR) and by insulin resistance index (IRI) based on glycemia and insulinemia during OGTT.Results. All groups were matched for age and body mass index (BMI). RBP-4 levels (μg/ml, mean±standard deviation) were higher in women with GDM vs. controls (53.9 ± 17.9 vs. 29.7 ± 13.9, p ≤ 0.001), with a trend towards higher RBP-4 in GDM compared with IG (38.0 ± 19.3, p = 0.07). There was no significant correlation between RBP-4 and age, BMI, insulin, IRI or HOMA-IR, but there was a moderate, significant negative correlation between RBP-4 and sVCAM-1 (r2 = 0.20, p = 0.001).Conclusions. RBP-4 levels are elevated in women with GDM, but do not correlate with IR indices and correlate negatively with sVCAM-1. The physiological significance of RBP-4 rise in women with GDM remains to be elucidated.