The exclusion criteria were (i) incomplete medical history or clinical examination results; (ii) serious infection, tumor, and other serious conditions; and (iii) pathological results indicating DN combined with NDRD. All patients were divided into three groups according to pathological pattern: DN or NDRD.
A total of 982 individuals were finally enrolled, comprising 350 patients with DN and 632 patients with NDRD. The age of the patients ranged from 19 to 85 years.
The exclusion criteria were the following: patients who had a confirmed diagnosis of renal diseases before they were diagnosed with type 2 diabetes; with a clinically confirmed diagnosis of NDRD, including lupus nephritis and Henoch-Schonlein purpura nephritis; with familial hereditary nephropathies, such as autosomal dominant polycystic kidney disease; and with an uncertain pathological diagnosis.
Renal biopsy indications: in clinical practice, the possible diagnosis of NDRD was confirmed by renal biopsy when the following situations occurred: gross/microscopic hematuria; elevated serum creatinine without obvious proteinuria; persistent massive proteinuria with normal renal function and no diabetic retinopathy.
Therefore proteinuria in Type2 DM may reflect Diabetic nephropathy or concurrent non-diabetic renal disease super imposed on DN, or NDRD only.
However, factors clinically associated with NDRD in Type 2 DM remains unclear.
The renal biopsy standard was consistent with the guideline for the 2008 Kidney Disease Outcomes Quality Initiative guidelines; the guidelines include the following clinical manifestations for suspected NDRD patients: naked eye/microscopic hematuria, elevated serum creatinine not accompanied by significant proteinuria, persistent large amounts of proteinuria with normal renal function, and no diabetic retinopathy.
Urinary proteins from 37 patients (19 with DN, 18 with NDRD) were collected; the clinical information of patients is shown in [Table 1].
In China, IgA nephropathy was the most frequently biopsy finding seen in all NDRD patients, followed by membranous nephropathy, mesangial proliferative glomerulonephritis, hypertensive nephrosclerosis, renal damage, minimal-change disease, focal segmental glomerulosclerosis, and crescentic glomerulonephritis .
As the DN and NDRD have different causes, their relationship, synergistic or independent, remains to be further studied.
This combination was obligatory to reduce the possibility that cases with proteinuria due to renal disease other than DN (NDRD) were included .
Out of the whole cohort, 175 patients were on hemodialysis including 90 diabetic patients and 85 NDRD patients.