Prevalence, Etiology and Clinical Characteristics of Biopsy Proven Non-Diabetic Renal Disease in a Population of 67 Diabetic Patients

Background: Diabetic nephropathy (DN) has been historically the major cause of kidney disease in diabetic patients. However, recent studies have found a high proportion of diabetic patients with biopsy proven Non-diabetic renal disease (NDRD) or NDRD superimposed on DN. These findings have resurfaced the interest in establishing which of these patients may benefit most from a kidney biopsy. Our study aims to enlighten the prevalence and etiology of biopsy proven NDRD and to explore clinical and morphologic differences encountered in the diabetic patient with NDRD. Methods: Medical records of all diabetic patients who underwent native kidney biopsy for suspected NDRD from January 2016 to December 2018 at Hospital Curry Cabral Centro Hospitalar Universitário de Lisboa Central, EPE, were analysed retrospectively. Results: We review medical records of 67 patients. All patients had a diabetes mellitus diagnosis at the time of biopsy and were biopsied for NDRD suspicion. In our population, 55.2% had DN (7.5% presented simultaneously DN and NDRD) and 41.8% had isolated NDRD. The most frequent causes of NDRD were IgA nephropathy (25%) and Chronic Interstitial Nephritis (10.8%). A shorter duration of diabetes had a statistically significant association with NDRD. Conclusions: Nearly half diabetic patients proposed to kidney biopsy have a NDRD. Since kidney biopsy is essential to establish the diagnosis and subsequently provide adequate treatment, this resource should be used in the diabetic diabetic patient with NDRD suspicion, especially in those with a shorter duration of diabetes. Additional data is necessary to establish which patients should be proposed to earlier kidney biopsies.