Prevalence and Spectrum of Nondiabetic Kidney Disease in Type 2 Diabetes Mellitus: An Eight-Year Retrospective Study

Background: Diabetic kidney disease (DKD) is the leading cause of chronic kidney disease (CKD) in patients with type 2 diabetes mellitus (T2DM). However, a considerable proportion of these patients develop nondiabetic kidney disease (NDKD), which has different therapeutic and prognostic implications. Objective: To evaluate the prevalence, clinical presentation, and histopathological spectrum of NDKD in T2DM patients undergoing renal biopsy. Methods: We retrospectively analyzed data from T2DM patients who underwent renal biopsy over an 8-year period. Patients with inadequate biopsies, prior renal transplants, or insufficient clinical data were excluded. Biopsy indications included atypical features such as nephrotic-range proteinuria, active urinary sediment, acute kidney injury (AKI), or absence of diabetic retinopathy (DR). Histopathological findings were categorized as: (1) pure DKD, (2) pure NDKD, and (3) NDKD superimposed on DKD. Results: A total of 255 patients were included. The mean age was 49.5 years, with a male-to-female ratio of 3.1:1. Median duration of diabetes was 3.9 years. Hypertension was present in 59% of patients. Nephrotic syndrome was the most common indication for biopsy (42%). Pure DKD was seen in 110 patients (43%), pure NDKD in 85 (33%), and NDKD superimposed on DKD in 60 (24%). Focal segmental glomerulosclerosis (FSGS) was the most frequent NDKD (29%). Conclusion: NDKD is a common finding in T2DM patients presenting with atypical renal features. Clinical and laboratory parameters alone are insufficient to reliably differentiate NDKD from DKD. Renal biopsy remains a crucial tool for accurate diagnosis, influencing treatment and prognosis.