Renal outcomes in patients with type 2 diabetes with or without coexisting non-diabetic renal disease

Aims: We sought not only to determine the independent predictors of non-diabetic renal disease (NDRD) but also to investigate the impact of NDRD on renal outcomes in patients with type 2 diabetes who underwent renal biopsy and were followed-up longitudinally. Methods: The present study was conducted by reviewing the medical records of 119 type 2 diabetic patients who underwent renal biopsy at Yonsei University Health System from January 1988 to December 2008. Results: Renal biopsy findings declared that 43 patients (36.1%) had diabetic nephropathy alone, 12 (10.1%) had NDRD superimposed on diabetic nephropathy, and 64 (53.8%) had only NDRD. On multivariate analysis, the absence of diabetic retinopathy, higher hemoglobin levels, and shorter duration of diabetes were independent predictors of NDRD in these patients. During the follow-up period, end-stage renal disease (ESRD) developed in 33 patients (27.7%). On multivariate Cox regression, higher serum creatinine levels, higher systolic blood pressure, longer duration of diabetes, and the presence of diabetic nephropathy were identified as significant independent predictors of ESRD. When the presence of diabetic retinopathy was included in the multivariate model, higher serum creatinine levels, higher systolic blood pressure, and the presence of retinopathy were shown to be independent predictors of ESRD. Conclusions: Since diabetic patients with NDRD have significantly better renal outcomes compared to patients with biopsy-proven diabetic nephropathy, it is important to suspect, identify, and manage NDRD as early as possible, especially in type 2 diabetic patients with short duration of diabetes and those without diabetic retinopathy or anemia.