Clinical Significance of Albuminuria in Patients with Diabetes

Abstract

There is a global consensus that early diabetic kidney disease (DKD) is characterized by persistent albuminuria. According to international guidelines, albuminuria is defined as a urinary albumin-to-creatinine ratio (ACR) ≥30 mg/g. Urinary albumin levels should be measured at least once a year. Moreover, albuminuria has been recognized as a predictor of cardiovascular disease.

In our cohort study including 3,231 diabetic patients, baseline albuminuria, defined as urinary ACR ≥30 mg/g, was found in 35.1 % of patients; and a decreased estimated glomerular filtration rate (eGFR), defined as eGFR <60 mL/min/1.73 m², was observed in 20.7 % of patients. The hazard ratio (HR) in each group stratified by albuminuria and eGFR was analyzed to simultaneously estimate the impact of these renal manifestations on renal outcomes. Compared to patients with normoalbuminuria and eGFR ≥60 mL/min/1.73 m², there was no significantly increased risk for renal endpoints among individuals with normoalbuminuria and eGFR <60 mL/min/1.73 m² [HR: 2.50; 95 % confidence interval (CI) : 0.99-6.33; p = 0.053]. In contrast, those with microalbuminuria and eGFR ≥60 mL/min/1.73 m² had a significantly increased risk for renal outcomes (HR: 4.98; 95 % CI: 2.82-8.80; p < 0.001). Therefore, albuminuria may be an independent predictor for the progression of DKD in Japanese patients with type 2 diabetes. In contrast, the level of eGFR is less likely to be associated with renal endpoints. Further studies are required to clarify the implications of albuminuria in diabetic patients.