SP391CLINICAL AND PATHOLOGICAL CHARACTERISTICS OF NONDIABETIC RENAL DISEASE IN TYPE 2 DIABETES PATIENTS

Introduction and Aims: Renal involvement in type 2 diabetes is primarily due to diabetic nephropathy (DN), however, a sizable proportion of diabetic patients could actually have nondiabetic renal disease (NDRD) or DN plus NDRD. The purposes of this study were to demonstrate the pathological features of NDRD and to determine the clinical parameters for distinguishing NDRD with or without DN from isolated DN in type 2 diabetes patients. Methods:Medical records of type 2 diabetes patients who underwent renal biopsy for suspicion of NDRD from January 2011 through November 2015 were analyzed retrospectively. Results: A total of 101 patients with type 2 diabetes and atypical features of DN were enrolled in this study. Mean age was 51.3+11.9 years, male to female ratio was 1.3:1, median duration of diabetes was 6 years (range, 1-20 years), mean serum creatinine was 2.8+2.2 mg/dL and proteinuria was 5.8+3.4 g/day. The most frequent indication for renal biopsy was recent onset of nephrotic syndrome (41%), followed by rapidly progressive renal failure (29%) and active urinary sediment (21%). The renal pathology revealed 51% of isolated DN, 20% of isolated NDRD, and 29% of DN plus NDRD. In patients with isolated NDRD, IgA nephropathy (35%), membranous nephropathy (25%), lupus nephritis (20%), membranoproliferative glomerulonephritis (5%), and IgM nephropathy (5%) accounted for the majority of cases, whereas, acute tubular necrosis (48%), and acute interstitial nephritis (41%) were main causes of NDRD superimposed on DN. Patients with NDRD with or without DN had a shorter duration of diabetes, lower frequency of diabetic retinopathy, better glycemic control, higher prevalence of active urinary sediment, and milder severity of proteinuria than patients with isolated DN (P <0.05). In multiple logistic regression analysis, short duration of diabetes (<8 years) (odds ratio [OR] 5.2; 95% confidence interval [CI] 1.5 to 17.6; P = 0.009) and microscopic hematuria (>5 erythrocytes per high-power field) (OR 4.7; 95% CI 1.2 to 17.8; P = 0.022) were independent predictors of NDRD. Conclusions: Judicious use of renal biopsy has unveiled NDRD with or without DN in nearly half of type 2 diabetes patients with atypical renal presentation: especially a short duration of diabetes and active urinary sediment. Our data show that IgA nephropathy and acute tubular necrosis was the most common renal pathology in patients with isolated NDRD and NDRD superimposed on DN, respectively.