Kidney Biopsy Indications in Type 2 Diabetes Patients

The purpose of the study is to evaluate the accuracy of kidney biopsies indications in patients with type 2 diabetes to diagnose non-diabetic renal disease based on canonical atypical features (Absence of diabetic retinopathy, Low or rapidly decreasing GFR, Rapidly increasing proteinuria or nephrotic syndrome and Presence of active urinary sediment. This study is a retrospective observational case only study, recruiting patients over 18 years old with type 2 diabetes who underwent kidney biopsy in five French nephrology centers between 2006 and 2015. Will be collected demographical, clinical and biological data at the time of the renal biopsy and at the last follow-up from the patients' medical charts. Indications for renal biopsy will be categorized as 1. Atypical feature of etiological significance in the presence of any atypical feature not listed below (including acute kidney injury as defined by the stage 1 of KDIG guidelines) 2. Brutal nephrotic syndrome in the absence of the above criterion 3. Rapid decline of GFR (defined as 50 % eGFR decline over \>1 week but \< 1 year) in the absence of criteria 1-2 4. Absence of proteinuria in the absence of criteria 1-3 5. Rapid increase of proteinuria in the absence of criteria 1-4 6. Presence of hematuria in the absence of criteria 1-5 7. Absence of diabetic retinopathy in the absence of criteria 1-6 Will be evaluate the actual probability to reach a non-diabetic renal disease for each of these indications. Will be also perform a classical analysis by assessing the association of clinical and biological feature such as HbA1c, diabetes duration, absence of diabetic retinopathy,… with the presence of a non-diabetic renal disease. In addition, the biopsy samples will be scored according to the RPS diabetic nephropathy classification to evaluate the prognostic value of this classification.