Assessment of retinol-binding protein-4, fibroblast growth factor-21, and dipeptidyl peptidase-4 in relation to obesity and insulin resistance of type 2 diabetes mellitus among Egyptian patients

Background/aim
The relation between obesity, inflammation, and insulin resistance (IR) shows that adipose tissue plays a significant secretory role. Adipokines such as retinol-binding protein-4 (RBP-4), fibroblast growth factor-21 (FGF21), and dipeptidyl peptidase-4 (DPP4) exhibit pleiotropic biological activities and might be valuable biomarkers involved in the pathogenesis of type 2 diabetes mellitus (T2DM). The present study aims to assess serum levels of RBP-4, FGF21, and DPP4 and correlate their relation with obesity and IR in Egyptian patients with T2DM.
Patients and methods
This study included 130 patients with T2DM (70 obese and 60 nonobese) enrolled from the inpatient and outpatient clinics of the National Institute of Diabetes and Endocrinology (NIDE), Cairo, Egypt, in addition to 70 age-matched and sex-matched healthy individuals (35 obese and 35 nonobese). Serum level assessments of RBP-4, FGF21, and DPP4 were carried out on all participants using Enzyme Linked Immuno-Sorbent Assay technique.
Results
Serum levels of RBP-4, FGF21, and DPP4 showed statistically significant differences in all studied groups (<0.01). RBP-4, FGF21, and DPP4 were all correlated positively with BMI, fasting insulin, and HOMA-IR. RPB-4 was negatively correlated with high-density lipoprotein-cholesterol. Both RBP-4 and FGF21 were significantly associated with IR (odds ratio=1.264; <0.001, and odds ratio=1.059; <0.01, respectively), whereas receiver operating characteristic curves analysis revealed that serum levels of RBP-4 were most significant [area under curve (AUC)=0.826, =<0.001], followed by FGF21 (AUC=0.774, <0.001) and finally DPP4 (AUC=0.677, <0.001).
Conclusions
Obesity and IR were found to be significantly associated with RBP-4, FGF21, and DPP4. They were higher in all obese groups, with the diabetic obese group having the highest concentrations. Of the three adipokines studied, RBP-4 has the strongest link. This finding will bolster the adipose-derived factors use as biomarkers and targets for treating and managing obesity and T2DM.