Challenge of Kidney Biopsy in Diabetic Patients: A Northwest Italy Large Cohort

Background: Diabetic kidney disease is one of the most severe long-term complications of diabetes. The aim of the study was to retrospectively analyze monocentric case history of kidney biopsies performed in diabetic patients over a period of 10 years. Patient’s data were collected both at the time of histological examination and during follow-up Methods: Data of renal biopsies (RB) performed in patients with diabetes mellitus from 1st January 2014 to 31th July 2023, were collected. Patient identification was performed by reviewing clinical histories and histopathological charts. Data on the indication for RB were collected from the medical report of the hospitalisation when the procedure was performed or from the visit when the indication was given. Results: 297 patients were included in the study, regardless of diagnostic suspicion and histological findings. Histological examination revealed diabetic nephropathy (DN) in 112 cases (group 1), DN associated with another kidney disease in 56 cases (group 2) and nondiabetic renal diseases alone in the remaining 129 cases (62%) (group 3). In group 2 the kidney disease most frequently associated with DN was focal and segmental glomerulosclerosis, FSGS followed by IgA nephropathy, IgAN. The histological examination led to specific therapeutic indications in 22 pts. In group 3 the most frequently observed kidney disease was FSGS followed by ANCA-vasculitis, membranous nephropathy and IgAN. In this population, histological examination led to a specific therapeutic indication in 67 pts. During a mean follow up of 41.6±31.8 months, 53 pts reached ESKD (16.5 months). In our population the presence of DN associated with another biopsy-proven nephropathy was especially prevalent. Having double nephropathy conferred a relative risk-RR for dialysis of 1.8089 (95% CI 1.0094 to 3.2415, p=0.0464). Conclusion: To our knowledge this is the largest cohorts of diabetic patients receiving renal biopsy even reported in a Western country. Our data proved kidney biopsy not to be an academic exercise in diabetic pts. Clinical and laboratory features do not predict histologic findings. Renal biopsy allowed the identification of unsuspecting nondiabetic kidney injuries and double nephropathies, which could be susceptible to different outcomes, and paved the pathway for treatment of potentially manageable histological changes.