Effect of Reducing Uric Acid on Insulin Sensitivity and Oxidative Status

It has been hypothesized that oxidative stress is involved in the pathogenesis of insulin
resistance associated with obesity. Circulating uric acid (UA) is the body's major endogenous
plasma antioxidant. Therefore, the investigators evaluated whether alterations in serum UA
concentration affect: 1) systemic and skeletal muscle oxidative stress, 2) total antioxidant
capacity, and 4) skeletal muscle insulin sensitivity during a hyperinsulinemic-euglycemic
clamp.

Inclusion Criteria:

- obese (BMI 30-45 kg/m²);

- serum UA concentration either ≥5 mg/dL or ≤4.0 mg/dL (297 µmol/L)],

Exclusion Criteria:

- renal dysfunction (serum creatinine >1.5 mg/dL);

- pregnancy or lactating;

- take urate-lowering agents, thiazide diuretics, prednisone or medications containing
aspirin or other salicylates;

- history of xanthinuria, type 2 diabetes or other significant organ system dysfunction;

- have G6PD deficiency;

- use hormone-replacement or oral-contraceptive therapy;

- smoke tobacco;

- anemic (Hb <10 g/dl)