Adiponectin and TNF-Alpha Differentially Mediate the Association Between Cystatin C and Oxidized LDL in Type 2 Diabetes Mellitus Patients

In individuals with type 2 diabetes mellitus (T2DM), elevated levels of both plasma and urinary cystatin C (Cys-C) contribute to increased oxidation, which in turn accelerates the oxidation of low-density lipoprotein (LDL). This process may worsen the development of atherosclerosis and cardiovascular disease by promoting endothelial dysfunction and inflammation. Despite its potential significance, the relationship between Cys-C and oxidized LDL (ox-LDL) in T2DM remains poorly understood. This study investigated the relationship between plasma and urinary Cys-C and ox-LDL levels in T2DM patients. The cohort included 57 patients with T2DM (mean age 61.14 ± 9.99 years; HbA1c 8.66 ± 1.60% and BMI 35.15 ± 6.65 kg/m²). Notably, 95% of the patients had hypertension, 82% had dyslipidemia, 59% had an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m², 14% had coronary artery disease (CAD), and 5% had a history of stroke. Plasma and urinary Cys-C and ox-LDL levels were measured using ELISA. Adipokine and cytokine levels were measured using the multiplex^® MAP Human Adipokine Magnetic Bead Panels. Spearman's correlation analysis revealed a significant positive correlation of plasma and urinary Cys-C with ox-LDL (r = 0.569, <i>p</i> = 0.0001 and r = 0.485, <i>p</i> = 0.0001, respectively). Multivariable regression analysis indicated that both plasma and urinary Cys-C were independently associated with ox-LDL, after adjusting for confounding factors (β = 0.057, <i>p</i> = 0.0001 and β = 0.486, <i>p</i> = 0.003, respectively). Stepwise linear regression identified TNFα and adiponectin as the strongest predictors of the relationship between urinary Cys-C and ox-LDL (β = 0.382, <i>p</i> = 0.0001; r² = 0.64), while adiponectin alone was the best predictor of the plasma Cys-C and ox-LDL association (β = 0.051, <i>p</i> = 0.005; r² = 0.46). Furthermore, adiponectin partly mediated the relationship between plasma Cys-C and ox-LDL, explaining 18% of the variance in this association. In contrast, TNFα partly mediated the relationship between urinary Cys-C and ox-LDL, accounting for 28% of the variance. This study emphasizes the complex interaction between Cys-C and ox-LDL in T2DM. It highlights the need for additional research involving larger patient cohorts to improve our understanding of the therapeutic potential of plasma and urinary Cys-C in conjunction with ox-LDL for managing complications associated with T2DM.