Urinary Sirtuin2/Creatinine Ratio Correlates with Severity of Albuminuria and Tubular Injury in Type 2 Diabetes Patients

Abstract Aims : The early diagnosis of kidney injury in type 2 diabetes (T2DM) is important to prevent the long-term damaging effects of kidney loss and is decisive for patient outcomes. This study was designed to investigate Sirtuin2 (SIRT2) expression and evaluate the performance of SIRT2 in T2DM patients. Methods : A total of 163 T2DM patients were divided into three groups according to their urinary albumin/creatinine ratio (UACR): normal to mildly increased (A1 group, UACR < 30 mg/g, n = 58), moderately increased (A2 group, UACR 30-300 mg/g, n = 52), and severely increased (A3 group, UACR > 300 mg/g, n = 53), with healthy individuals (NC group, n = 40) as controls. SIRT2 levels in serum and urine were measured using an enzyme-linked immunosorbent assay (ELISA). Immunoturbidimetry was employed to detect biomarkers of kidney injury such as urinary albumin, α1-microglobulin, β2-microglobulin, and retinol-binding protein. After urinary creatinine correction, they were expressed as USCR, UACR, UαCR, UβCR, and URCR, respectively. Results : We found USCR levels in the A3 group were highest than those in NC and A1 groups, and USCR levels above the median level were linked to higher levels of UACR, UαCR, UβCR, and URCR. However, no significant difference existed in serum SIRT2 level among all groups. Spearman correlation analysis revealed that USCR was positively correlated with UACR, UαCR, UβCR, and URCR and was negatively linked to eGFR. ROC curve demonstrated that USCR had high sensitivity or specificity for distinguishing glomerular and tubular injury in T2DM patients. Logistic ordered multi-classification regression analysis confirmed that USCR remained a risk factor for severity of albuminuria in T2DM patients after adjustment for confounding factors. Conclusion : Urinary SIRT2 is not only an effective indicator for glomerular and tubular injury in T2DM patients but also an important risk factor for severity of albuminuria.