Elevated serum retinol-binding protein 4 concentrations are associated with chronic kidney disease but not with the higher carotid intima-media thickness in type 2 diabetic subjects

To examine the association of serum retinol-binding protein 4 (RBP4) concentrations with carotid intima-media thickness (CIMT) in type 2 diabetic subjects with chronic kidney disease (CKD). A total of 239 type 2 diabetic patients (64 +/- 13 years, 154 males) were divided into two groups: one with CKD, defined as estimated glomerular filtration rate (eGFR) below 60 ml/min/1.73m(2) (n = 86), and one without (n = 153). We recorded clinical and biochemical data as well as CIMT. The patients with CKD were older, had had diabetes mellitus longer, and had higher incidence of hypertension, dyslipidemia and microalbuminuria than those without. They also had higher serum concentrations of RBP4 (44.8 +/- 6.4 vs 39.5 +/- 4.9 mu g/mL, p < 0.001), higher mean CIMT (0.75 +/- 0.16 vs 0.69 +/- 0.14 mm, p = 0.0070), and higher incidence of carotid plaques (27.9 vs 11.8 %, p = 0.002). The RBP4 were negatively correlated with eGFR (r = -0.514, p < 0.001). However, the RBP4 were not correlated with mean CIMT (r = 0.065, p = 0.318). Moreover, when dividing the patients into two groups by the mean CIMT, those with mean CIMT above 0.71 mm did not have different RBP4 concentrations compared with those below (41.5 +/- 5.7 vs 41.3 +/- 6.3 mu g/mL, p = 0.856). In conclusion, we observed an elevation of serum RBP4 concentrations and CIMT levels in type 2 diabetic subjects with CKD. However, the elevated RBP4 were not associated with the higher CIMT among these patients.