Renal handling of uric acid in patients with type 1 diabetes in relation to glycemic control

BACKGROUND: The aim of the study was to compare the renal handling of uric acid (UA) in 16 patients with type 1 diabetes without renal failure (age 34.8 +/- 13.3 years) and in 15 healthy subjects (age 34.9 +/- 12.6 years). METHODS: Creatinine clearance (Cr-Cl), clearance of uric acid (UA-Cl), fractional excretion of uric acid (UA-FE), and 24-h urinary UA excretion (UA-U) were determined. Glycemic control was assessed using fasting glucose, glycated hemoglobin and fructosamine tests. RESULTS: Patients with diabetes had significantly (p < 0.0001) lower serum UA concentrations compared to control group (2.8 +/- 0.7 vs. 5.7 +/- 0.8 mg/dl), and higher urinary UA excretion (813 +/- 107 vs. 423 +/- 40 mg/day), UA clearance (21.9 +/- 7.1 vs. 5.2 +/- 0.9 mL/min) and fractional UA excretion (17.1 +/- 5.5 vs. 4.8 +/- 1.3%), with higher creatinine clearance (129 +/- 16 vs. 111 +/- 12 mL/min, p < 0.005). In patients with diabetes there was a strong negative correlation between serum UA concentration and UA 24-h excretion (R = -0.79; p < 0.001). Fractional UA excretion correlated with fasting glycemia and HbA1c (R = +0.51 and +0.53; p < 0.05). CONCLUSIONS: In type 1 diabetes there is significant UA renal clearance increase, which is higher with poor glycemic control. It leads to hypouricemia despite an approximately twofold UA excretion increase and therefore despite increased UA synthesis.