Non-diabetic renal disease in type 2 diabetes mellitus: Study of renal - retinal relationship

Diabetic nephropathy (DN) has become the leading cause of end-stage renal disease worldwide. Non-diabetic renal disease (NDRD), is known to occur in diabetic patients. The renal and retinal relationship in type 2 diabetes mellitus (T2DM) with nephropathy is not uniform. This study was carried to study the histological spectrum of nephropathy in type 2 diabetic patients with proteinuria and its relationship with diabetic retinopathy (DR). Total 31 (males - 26; females - 5) proteinuric type 2 diabetic patients were studied. Average age of patients was 50.7 years. Nephrotic syndrome was noted in 21 (67.7%) patients. Overall, isolated DN, NDRD and NDRD superimposed on DN (mixed lesion) were observed in 12 (38.7%), 13 (41.9%) and 6 (19.4%) cases, respectively. DR was absent in 21/31 (67.7%) cases. The spectrum of nephropathy in patients without DR included: DN in 6 (28.57%), NDRD in 12 (57.14%) and mixed lesion in 3 (14.29%). Kidney histology in patients with DR (n-10) revealed DN in 6 (60%), NDRD in 1 (10%) and mixed lesion in 3 (30%) patients. Thus, absence of DR favors NDRD but does not exclude DN because isolated DN was noted in 28.57% cases in absence of DR. Similarly biopsy proven NDRD (pure NDRD; 10% and mixed lesion; 30%) was noted in 40% of cases in presence of DR. In summary, patients with T2DM had higher incidence of NDRD. DR is less frequent (32.3%) in type 2 diabetes and is a poor predictor of type of nephropathy. Hence, renal biopsy is essential for precise diagnosis of nephropathy in patients with T2DM.