Association of Urinary Vitamin D-binding Protein and Megalin as Biomarkers for Diabetic Nephropathy in Type 2 Diabetes Mellitus in Qatari Patients

Abstract

Abstract Background: Nephropathy is a common complication of type 2 diabetes mellitus (T2DM). Previous studies revealed that T2DM patients with nephropathy have higher concentrations of urinary Vitamin D Binding Protein (VDBP) that carries vitamin D to the target tissues, and megalin that mediates endocytosis in the proximal tubule than those who are healthy. Methodology: 196 urine samples with their blood data were obtained from Qatar Biobank, of which 21 samples were measured for VDBP and megalin using enzyme-linked immunosorbent assay (ELISA). They were divided intothree groups; group 1 (control group with eGFR ≥ 90 mL/min/1.73 m²), group 2 (T2DM patients with eGFR ≥ 90 mL/min/1.73 m²) and group 3; (T2DM patients with eGFR < 90 mL/min/1.73 m²). Results: Urinary VDBP and Megalin levels were non-significantly elevated in T2DM patients with DN (P=0.198) and (P=0.293) respectively. Moreover, a weak negative correlation was observed between the urinary VDBP and Megalin levels with eGFR (r=-0.326, P=0.149) and (r=-0.315, P=0.165) respectively. Conclusion: Previous studies revealed that uVDBP and Megalin are potential biomarkers for DN in T2DM patients. However, the current study reveals that urinary VDBP and megalin levels were non-significantly elevated in T2DM patients with DN. Furthermore, eGFR showed a weak negative correlation with urinary VDBP and megalin levels. However, it is suggested that these results could be due to some limitations. Further tests should be performed on larger sample size to confirm the association of Megalin and VDBP in T2DM nephropathy.