Background: Diabetes is the main cause of ESRD, and albuminuria is a major determinant of adverse renal outcome. Likewise, albuminuria is an intermediate risk factor of chronic kidney disease (CKD) progression in diabetic patients. Our aim was to compare the rate of renal decline in diabetic and non-diabetic CKD patients (GFR < 50 ml/min) with comparable levels of albuminuria.
Methods: In this observational study, 333 patients (age 67 +/- 15 years, 46% diabetics) were included during a 7.5-year period. The mean follow-up was 30 +/- 18 months (range 4-79). The influence of study variables was evaluated applying a time-dependent Cox model and slope-based outcome using a linear regression model.
Results: The diabetes condition was associated with adverse outcome in univariate analysis, and after adjusting for age, sex and systolic blood pressure. However, when controlling for albuminuria (a time-dependent covariate), diabetes did not show any association with outcome. In addition, the mean slope of renal decline was similar in diabetic and non-diabetic patients when controlling for albuminuria. The urinary albumin-creatinine ratio was a robust predictor of poor outcome in uni- and multivariate models. In the diabetic group, time-varying glycosilated haemoglobin did not influence renal outcome in the Cox model, and time-varying albuminuria remained a strong predictor of outcome.
Conclusions: Diabetic patients have a poorer renal outcome, but at comparable levels of albuminuria renal decline is similar in diabetic and non-diabetic patients. Albuminuria is a risk factor for renal decline, and the main target to delay progression in patients, diabetics or non-diabetics, with moderate to advanced CKD.