Year: 2026 | Month: July | Volume: 13 | Issue: 7 | Pages: 476-479
DOI: https://doi.org/10.52403/ijrr.20260749
Diabetic Retinopathy Confirms but Does Not Exclude Diabetic Nephropathy in Type 2 Diabetes: A Renal Biopsy Study of Diagnostic Accuracy and the Non-Diabetic Kidney Disease Spectrum
Dr. Sagar Bagalkot S1, Dr. M. S. Prakash2
1Senior Resident, Department of Nephrology, Rajarajeshwari Medical College and Hospital, Bengaluru, India.
2Former Head of the Department and Professor, Department of Nephrology, Rajarajeshwari Medical College and Hospital, Bengaluru, India.
Corresponding Author: Dr. Sagar Bagalkot S
ABSTRACT
Background. Non-diabetic kidney disease (NDKD) accounts for a clinically important proportion of renal disease in patients with type 2 diabetes mellitus (T2DM) undergoing kidney biopsy, and its management and prognosis differ from those of isolated diabetic nephropathy (DN). Absence of diabetic retinopathy (DR) is a widely cited clinical clue to NDKD. We evaluated the diagnostic performance of DR for predicting biopsy-proven DN and described the spectrum of NDKD in T2DM patients biopsied at a single centre.
Methods. Records of 60 T2DM patients who underwent renal biopsy were analysed. Biopsy diagnosis was the reference standard; DR (present/absent) was the index test. Sensitivity, specificity, predictive values, likelihood ratios and accuracy were calculated with 95% confidence intervals (CI); the DR–biopsy association was tested by Fisher's exact test. Baseline features were compared between groups and the NDKD spectrum described.
Results. Isolated DN was present in 44/60 (73.3%) and NDKD (including one mixed case) in 16/60 (26.7%). DR predicted DN with sensitivity 56.8% (95% CI 42.2–70.3), specificity 93.8% (71.7–98.9), PPV 96.2% (81.1–99.3), NPV 44.1% (28.9–60.5) and accuracy 66.7%; LR+ 9.09 and LR− 0.46 (Fisher p = 0.0004). Nearly half of DN patients (19/44, 43.2%) had no retinopathy. NDKD patients had markedly shorter diabetes duration (median 2 vs 12 years, p < 0.001), lower HbA1c (p = 0.034), more frequent low serum C3 (p = 0.016) and less advanced IFTA (p = 0.007). The commonest NDKD lesion was focal segmental glomerulosclerosis (25.0%).
Conclusions. In biopsied T2DM patients, the presence of retinopathy strongly rules in DN (high specificity and PPV), but its absence is a poor rule-out (low NPV). Short diabetes duration and low complement are more discriminating pointers to NDKD, and biopsy selection should not rest on retinopathy status alone.
Keywords: diabetic nephropathy; non-diabetic kidney disease; diabetic retinopathy; renal biopsy; type 2 diabetes mellitus.
[PDF Full Text]