Non-diabetic renal disease with or without diabetic nephropathy in type 2 diabetes: clinical predictors and outcome

Abstract

Background: Renal involvement in type 2 diabetes is mostly due to diabetic nephropathy (DN), but a subset of diabetic patients could present with pure non-diabetic renal disease (NDRD) or NDRD superimposed on DN. We conducted a prospective cohort study to identify the underline renal pathology in type 2 diabetic patients with defined clinical criteria for renal biopsy. Methods: A total of 46 patients (27 female, mean age of 48.9 ± 11.9 years) with type 2 diabetes mellitus (DM) and atypical features of DN with unexpected proteinuria, hematuria, and/or renal impairment were enrolled in this study. Results: Of 46 patients with type 2 diabetes, 16 (34.8%) had DN, 20 (43.5%) had NDRD, and 10 (21.7%) had NDRD superimposed on DN. Membranous nephropathy (34%) was the most common NDRD. Patients with NDRD had a lower frequency of diabetic retinopathy (5%), shorter duration of diabetes, higher range of proteinuria, and better kidney survival. In multiple logistic regression analysis, only lack of diabetic retinopathy was independent predictor of NDRD. Positive and negative predictive value of diabetic retinopathy (DR) for diabetic nephropathy was 94 and 68%, respectively. Conclusion: Kidney biopsy is strongly recommended for patients with type 2 diabetes and atypical renal presentation for DN, particularly in the absence of DR. This approach could lead to diagnosis of NDRD with better renal survival.