Serum Uric Acid and Risk of CKD in Type 2 Diabetes.

BACKGROUND AND OBJECTIVE

Serum uric acid may predict the onset and progression of kidney disease, but it is unclear whether uric acid is an independent risk factor for diabetic nephropathy. Our aim was to study the relationship between uric acid levels and the development of CKD components in patients with type 2 diabetes.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Longitudinal study of a cohort of patients with type 2 diabetes from the database of the Italian Association of Clinical Diabetologists network. From a total of 62,830 patients attending the diabetes centers between January 1, 2004, and June 30, 2008, we considered those with baseline eGFR values ≥60 ml/min per 1.73 m2 and normal albumin excretion (n=20,142). Urinary albumin excretion, GFR, and serum uric acid were available in 13,964 patients. We assessed the association of serum uric acid quintiles with onset of CKD components by multinomial logistic regression model adjusting for potential confounders. We calculated the relative risk ratios (RRRs) for eGFR <60 ml/min per 1.73 m2, albuminuria, and their combination at 4 years.

RESULTS

At 4-year follow-up, 1109 (7.9%) patients developed GFR <60 ml/min per 1.73 m2 with normoalbuminuria, 1968 (14.1%) had albuminuria with eGFR ≥60 ml/min per 1.73 m2, and 286 (2.0%) had albuminuria with eGFR <60 ml/min per 1.73 m2. The incidence of eGFR <60 ml/min per 1.73 m2 increased in parallel with uric acid quintiles: Compared with the lowest quintile, RRRs were 1.46 (95% confidence interval [CI], 1.14 to 1.88; P=0.003), 1.44 (95% CI, 1.11 to 1.87; P=0.006), 1.95 (95% CI, 1.48 to 2.58; P<0.001), and 2.61 (95% CI, 1.98 to 3.42; P<0.001) for second, third, fourth, and fifth quintiles, respectively. Serum uric acid was significantly associated with albuminuria only in presence of eGFR <60 ml/min per 1.73 m2.

CONCLUSIONS

Mild hyperuricemia is strongly associated with the risk of CKD in patients with type 2 diabetes.