Non diabetic renal disease frequency in renal biopsies of diabetic patients

Objective: Diabetes is the most important cause of chronic kidney disease in our country and in the world. However, there are also studies showing high rates of non-diabetic renal disease in diabetic patients. This distinction can only be made by renal biopsy. The aim of our study is to determine the frequency of non-diabetic renal disease in diabetic patients with renal biopsy and its relationship with demographic, clinical and laboratory findings. Method: The data of 131 patients with type 2 DM who underwent renal biopsy between January 2010 and August 2022 at Meram Medical Faculty Nephrology Clinic were retrospectively analyzed. Sociodemographic data of the patients, duration of diabetes, diabetic retinopathy, history of coronary artery disease and cerebrovascular accident, comorbidities such as hypertension, hyperlipidemia and low ejection fraction heart failure, body mass index, pre-biopsy renin-anijotensin aldosterone system (RAS) blocker use, blood pressure values was recorded. Creatinine, estimated glomerular filtration rate (eGFR), HbA1c, serum albumin and lipid values, proteinuria (g/day) and albuminuria (g/day) levels were recorded. According to the pathology results, the patients were divided into two groups as diabetic nephropathy (DN) and non-diabetic renal disease (NDRD). Statistical analysis of the data was performed using the SPSS 18.0 package program. Results: 131 diabetic patients who underwent renal biopsy were analyzed; 45.8% (n=60) were female, mean age was 55.32±11.62 years, median diabetes duration was 4 (2-8) years. The most common biopsy cause was nephrotic level proteinuria (n=71), followed by hematuria and proteinuria (n=27), acute kidney injury (n=25), and isolated hematuria (n=8). Pathologically, non-diabetic renal disease was detected in 71.8% (n=94) of the patients. The most common NDRD diagnoses are; membranous nephropathy (n=32, 24.4%), FSGS (n=13, 9.9%), and Ig A nephropathy (n=111, 8.4%). Diabetes duration and diabetic retinopathy rate were significantly higher in the group with diabetic nephropathy (p<0.001, p<0.001). The rate of using antilipidemic drugs before biopsy was also higher in this group (p=0.025). Total cholesterol, triglyceride (TG), low-density lipoprotein and very low-density lipoprotein (VLDL) levels were significantly higher in the NDRD group (p values, respectively; p=0.005; p=0.007; p=0.011; p=0.001). In single and multiple regression analyzes, it was observed that diabetic retinopathy and long diabetes duration increased the risk of diabetic nephropathy (p<0.01). Conclusion: In our study, more than half of the patients (71.8%) were diagnosed with non-diabetic renal disease, and most of them were glomerulonephritis. Absence of retinopathy and short duration of diabetes were observed to be associated with non-diabetic renal disease in type 2 diabetic patients. The fact that patients do not have a known history of hyperlipidemia and anti-lipidemic drug use and high lipid values may be warning signs for nephrotic syndrome. We think that renal biopsy should be kept in mind in type 2 diabetic patients without retinopathy, short duration of diabetes, and hyperlipidemia, one of the components of nephrotic syndrome. Keywords: Diabetic kidney disease, diabetic nephropathy, non-diabetic renal disease, renal biopsy