Serum uric acid is independently associated with diabetic nephropathy but not diabetic retinopathy in patients with type-2 diabetes mellitus.

Background: This study aims to investigate the relationship between serum uric acid (SUA) and the severity of diabetic nephropathy (DN) and diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (T2DM). Methods: A total of 2961 patients were enrolled in the present cross-sectional study. The severity of DN was determined by 24-hour urinary albumin excretion (UAE), which was classified as normal (UAE <30 mg/24 h), microalbuminuria (UAE: 30-299 mg/24 h), and macroalbuminuria (>= 300 mg/24 h). The severity of DR was determined by non-mydriatic retinal photography and was classified as non-diabetic retinopathy (NDR), non-proliferative diabetic retinopathy (NPDR), and proliferative DR (PDR). Results: Patients with high SUA levels (>= 420 mu mol/L for males and >= 360 mu mol/L for females) had a significantly higher prevalence of DN (UAE >= 30 mg/24 h, 39.3% vs 26.3%; p < 0.001), higher UAE levels (140 +/- 297 vs 63 +/- 175 mg/24 h; p < 0.001), and lower estimated glomerular filtration rate (eGFR; 79.3 +/- 26.8 vs 96.8 +/- 19.6 mL/min/1.73 m(2); p < 0.001), when compared with patients with normal SUA levels. However, the prevalence of DR, NPDR, or PDR did not differ. Furthermore, the concentration of SUA was higher in patients with higher severity of DN (all, p < 0.001) and patients with PDR (compared with NDR or NPDR, p < 0.05). SUA levels were positively associated with male gender, body mass index, the use of diuretics, triglyceride, low-density lipoprotein, and UAE levels, whereas they were negatively correlated with high-density lipoprotein, fasting blood glucose, glycosylated hemoglobin, and eGFR. After adjustment, SUA remained significantly associated with UAE (r = 0.069, p < 0.001). Conclusion: For patients with T2DM, higher SUA levels are associated with higher UAE, lower eGFR, and higher prevalence of DN, but not DR.