Serum retinol binding protein 4 level is related with renal functions in Type 2 diabetes

Aim : We aimed to evaluate the metabolic parameters and diabetes complications which would probably affect the serum retinol-binding protein 4 (RBP4) levels in Type 2 diabetic individuals. In addition to serum RBP4 concentration, the levels of its ligands, serum retinol and transthyretin (TTR) were also considered in this evaluation. Subjects and methods : Serum RBP4, retinol, and TTR levels were measured in 53 Type 2 diabetic subjects and 30 body mass index (BMI)-matched controls. The molar ratios of RBP4 to retinol and RBP4 to TTR were compared. Results : While the RBP4 values were similar to those in the control group in Type 2 diabetic patients, the molar ratio of RBP4 to TTR was found to be higher than that of the control group. The serum RBP4 levels in patients who had retinopathy and macrovascular disease were similar to those in patients who did not. However, the RBP4 levels, molar ratios of RBP4 to retinol and RBP4 to TTR in micro-macroalbuminuric patients were found to be significantly higher than in normoalbuminuric subjects and controls. There was no correlation between the RBP4 levels and the patients’ age, BMI, duration of diabetes, LDL, triglyceride, serum creatinine, and glycated hemoglobin values. Micro-macroalbuminuria and estimated glomerular filtration rate were independent determinants for increased serum RBP4 levels. Conclusion : According to the data obtained from this study, diabetic retinopathy and cardiovascular complications do not affect the serum RBP4 level in Type 2 diabetes. Renal functions rather than the metabolic factors of diabetes determine the RBP4 level and its relation with its ligands.