Non-diabetic renal disease in type 2 diabetes mellitus

Aim: The aim of this analysis of renal biopsies in people with type 2 diabetes was to know the prevalence and nature of non-diabetic renal disease (NDRD) and to note its correlation with the duration of diabetes, extent of proteinuria and presence or absence of retinopathy. Methods: From January 2000 to December 2004, 160 people with type 2 diabetes with clinically suspected NDRD underwent renal biopsy reported by a single pathologist. The case records of these patients were retrospectively analysed. Based on the biopsy findings, patients were grouped as Group I, isolated NDRD; Group II, NDRD with underlying diabetic glomerulosclerosis; and Group III, isolated diabetic glomerulosclerosis. The relation of histology with clinical profile in each group was noted and statistically analysed using strata 6 software. Results: Of the 160 patients studied, 118 were males and 42 were females (2.8:1). The average age was 51.35 years (30-79). Indications for renal biopsy included: nephrotic syndrome in 55 (34.37%), acute renal failure (AFF) in 49 (30.62%), rapidly progressive renal failure (RPRF) in 24 (15%), absent retinopathy in 19 (11.87%), haematuria in 10 (6.25%) and acute on chronic renal failure (CRF) in three (1.87%) patients. Group I included 68 patients (42.50%), Group II included 48 patients (30%) and Group III included 44 patients (27.50%). The mean duration of diabetes was 5.37, 10.12 and 6.86 years in Groups I, II and III respectively. The duration of diabetes was significantly less in Group I compared with Group II and III combined (5.37 vs 8.53; P< 0.001). Diabetic retinopathy was absent in 61 (38.13%) patients, of whom 41 (67.21%) had isolated NDRD. The most common NDRD were acute interstitial nephritis (18.1%), post infectious glomerulonephritis (17.24%), membranous nephropathy (11.20%) and focal segmental glomerulosclerosis (7.75%). Conclusions: Prevalence of NDRD (either isolated or superimposed on underlying diabetic glomerulosclerosis) is very high in appropriate clinical settings. The shorter duration of diabetes and the absence of retinopathy, especially when associated with nephrotic proteinuria, strongly predict NDRD.