Characterizing predictors of non-diabetic kidney disease (NDKD) in diabetic patients.

Background: Diabetic kidney disease (DKD) is the chief cause of renal involvement in diabetic patients. It is primarily a clinical diagnosis. Non-diabetic kidney disease (NDKD) may be missed if they are not biopsied. In this study, we describe the spectrum of NDKD and evaluate the predictors considered for planning a biopsy in diabetic patients with kidney disease.

Methods: In a retrospective cohort study, diabetic patients who underwent kidney biopsy at our centre between May 2006 and July 2019 were evaluated for NDKD.

Results: 321 diabetic patients who underwent kidney biopsy were analyzed. Mean age was 49.3 ± 12.4 years and 71% were males. 75.8% patients had hypertension and 25.2% had diabetic retinopathy. Based on the kidney biopsy, patients were classified as DKD-127 (39.6%), NDKD-179(55.8%) and combined DKD + NDKD-15(4.7%). Overall, the most commonly diagnosed pathology was membranous nephropathy-MN (17%), followed by IgA nephropathy (16.0%) and focal segmental glomerulosclerosis-FSGS (14.9%). In patients with DKD + NDKD, IgA nephropathy (53.3%) was predominant. 165 (51.4%) patients had a diagnosis potentially amenable to a specific therapy. On multivariate analysis, female gender [OR 2.07 (1.08-3.97), p = 0.02], absence of diabetic retinopathy [OR 7.47 (3.71-15), p < 0.001] absence of hypertension [OR 3.17 (1.56-6.45), p = 0.001] and duration of diabetes ≤ 24 months [OR 3.67(1.97-6.84), p < 0.001], were independent predictors for NDKD while the absence of nephrotic range proteinuria [OR 1.73 (0.98-3.05), p 0.05] showed a trend towards significance.

Conclusions: Astute use of kidney biopsy can detect potentially treatable NDKD in a large number of diabetic patients with glomerular diseases being the predominant diagnosis. A combination of risk factors needs to be considered to guide the need for kidney biopsy in diabetic patients.