Evaluation of irisin, retinol-binding protein 4, and leptin serum levels as biomarkers of macrovascular complications involvement in Saudi type 2 diabetes mellitus. A case-control study

Objectives: To evaluate adipokine serum values of irisin, retinol-binding protein 4, and leptin in Saudi cases with type 2 diabetes mellitus (T2DM) for providing markers of T2DM macrovascular complications. Methods: This case-control research was carried out at Erfan Hospital, Jeddah, Saudi Arabia. The study included 138 subjects, classified into 3 groups: 46 T2DM patients with macrovascular complications, 46 T2DM without macrovascular complications, and 46 controls. Participants evaluated clinically and some biochemical parameters were measured. Results: Diabetic with and without macrovascular complications showed elevation of retinol-binding protein 4 (RBP4) and leptin; decreased irisin serum levels versus controls. Serum irisin was lower (p=0.007), while RBP4 was higher (p<0.0001) in T2DM patients with macrovascular complications versus without. Irisin showed negative correlations with fasting blood glucose (FBG), insulin, homeostatic mode l assessment of insulin resistance (HOMA-IR), RBP4, hemoglobin A1C (HbA1C), triglyceride, cholesterol, and low-density lipoprotein cholesterol. While RBP4 showed positive correlations with fasting blood glucose, insulin, HOMA-IR, leptin, and HbAlc; but a negative association with high-density lipoprotein cholesterol. Conclusion: Type 2 DM patients had raised RBP4 and leptin, but lower irisin levels versus controls. Irisin was lower, but RBP4 was higher in T2DM patients with macrovascular complications versus without, suggesting T2DM patients in pro-inflammatory conditions. These results suggested that irisin is protective, while RBP4 is a risk factor for T2DM macrovascular complications.