Evaluation of renal biopsy samples of patients with diabetic nephropathy

To evaluate the usefulness of renal biopsy in the overall management of patients with diabetes mellitus (DM), we examined the relationship between the clinical parameters and histopathological findings of renal biopsy samples.

Renal biopsy specimens were obtained from 109 type 2 diabetic patients with proteinuria. Samples were divided into the following two groups: Diabetic Nephropathy (DN) group (n=80) had typical diabetic lesions without other renal diseases, complication group (n=29) had diabetic lesions with other renal diseases. Furthermore, DN group was subdivided into two subgroups: slow progressive group (SP group, n=32), the level of serum creatinine (s-Cr) was normal at the time of renal biopsy and three years after renal biopsy, and fast progressive group (FP group, n=14), the level of s-Cr was normal at the time of renal biopsy but more than doubled three years after renal biopsy.

The level of total protein was significantly lower and HbA1c significantly higher in the DN group than in the Complication group. However, other clinical parameters were not significantly different between the two groups. Urinary protein, systolic and diastolic blood pressure in FP group were significantly higher than in SP group. The percentage of sclerotic glomeruli, the severity of mesangial expansion, tubular injury and cell infiltration were significantly greater in FP than in SP group.

Our results indicated that a complete evaluation of renal pathology in DM could not be made by clinical parameters only, and that the progression of DN could be accurately predicted by histopathological evaluation. Therefore, this study emphasizes the importance of renal biopsy in the overall management of patients with DM and/or DN.