Serum Uric Acid to Serum Creatinine ratio and CV risk assessment in non albuminuric-DKD

Background: Approximately 40% of patients with type 2 diabetes (T2DM) manifest loss of renal function without albuminuria, configuring a new phenotype of diabetic kidney disease (DKD) whose cardiovascular (CV) risk is still under debate. Serum uric acid (SUA), the last byproduct of purine metabolism, emerged as modifiable CV risk factor but it should be adjusted for renal function through creatinine. The aim of this study was to evaluate the relationship between the SUA to serum creatinine ratio (SUA/SCr) and CV risk among subjects with non albuminuric-DKD (NA-DKD). Methods: SUA/Scr was evaluated in 192 subjects with T2DM stratified according to estimated glomerular filtration rate (eGFR) and urinary albumin to creatinine ratio (UACR) into four groups: controls (N=58, UACR<30 mg/g and eGFR≥60 mL/min/1.73 m²), A-DKD (N=50, Albuminuric-DKD, UACR≥30 mg/g and eGFR≥60 mL/min/1.73 m²), NA-DKD (N=44, UACR<30 mg/g and eGFR<60 mL/min/1.73 m²), AL-DKD (N=40, Albuminuric and Low eGFR-DKD; UACR≥30 mg/g and eGFR<60 mL/min/1.73 m²). We then evaluated the relationship between SUA/SCr and markers of CV and renal damage such as Pulse wave velocity (PWV), intima-media thickness (IMT), presence of carotid atherosclerotic plaque, and renal resistive index (RRI). Results: Subjects with NA-DKD, compared to controls, showed lower SUA/SCr (4.7±1.5 m/s vs 6.7±1.8 m/s, p<0.0001) but higher SUA (6.1±1.6 mg/dl vs 5.0±1.3 mg/dl, p=0.0002), PWV (11.8±3.0 m/s vs 9.9±3.3 m/s, p=0.03), RRI (0.76±0.10 vs 0.71±0.08, p=0.04), and prevalence of carotid atherosclerotic plaque (59% vs 36%, p=0.09). Patients with A-DKD had higher SUA/SCr compared to those with NA-DKD, but still lower if compared with controls (6.1±1.7 m/s vs 4.7±1.5 m/s, p<0.0001 and 6.1±1.7 m/s vs 6.7±1.8 m/s, p<0.008 respectively). We noted no significant differences concerning the other markers of CV and renal damage. After multiple regression analysis, we found that SUA/SCr was significantly correlated to PWV (β=-0.32, p=0.049). Conclusions: SUA/SCr might be considered as a prognostic tool to recognize people with NA-DKD at higher risk for adverse CV events.