Role of elevated serum uric acid levels at the onset of overt nephropathy in the risk for renal function decline in patients with type 2 diabetes

AIMS/INTRODUCTION Despite the use of intensive therapies, declining renal function is often observed during the overt nephropathy stage of type 2 diabetes. We aimed at investigating the role of serum uric acid (SUA) levels at the onset of overt nephropathy in the risk of renal function decline in type 2 diabetes patients. MATERIALS AND METHODS The present cohort study included 290 type 2 diabetes patients who were followed from the onset of overt nephropathy. The relationship between SUA and declining renal function was assessed using Cox regression models after adjusting for known risk factors. RESULTS Over a median 4.8-year follow-up period, 85 patients (4.9/100 person-years) showed serum creatinine (Cr) doubling with a total cumulative incidence of 71.9% at 20 years of follow up. The highest SUA tertile resulted in significantly a higher incidence (7.7/100 person-years) and cumulative incidence at 20 years (85.7%) than the middle (3.9/100 person-years, 54.2%) and lowest (3.0/100 person-years, 55.5%) tertiles. The univariate Cox hazard model resulted in significant risks for Cr doubling related to female sex, short diabetes duration, smoking and elevated levels of low-density lipoprotein cholesterol (LDL-c), glycated hemoglobin and SUA tertiles. SUA tertiles remained statistically significant in the multivariate model (highest vs lowest hazard ratio 2.68, 95% confidence interval 1.48-5.00, P = 0.0009). CONCLUSIONS Elevated SUA levels within the normal range (men >6.3 mg/dL, women >5.1) at the onset of overt nephropathy resulted in an increased risk for declining renal function in type 2 diabetes patients.