Clinical features of non-diabetic renal diseases in patients with type 2 diabetes
Introduction
Diabetic nephropathy (DN) is a major cause of end-stage renal disease. The characteristic histopathological feature of DN is diabetic glomerulosclerosis characterized by nodular lesions, diffuse lesions and exudative lesions associated with tubulointerstitial and vascular lesions. While persistent proteinuria is the most characteristic feature of DN, non-diabetic renal diseases (NDRD) must be identified in diabetic patients with proteinuria. It is important to determine the clinical predictive factors for NDRD in diabetic patients because renal biopsy is necessary to diagnose NDRD. We performed renal biopsies in diabetic patients with persistent proteinuria when NDRD was suspected based on the atypical clinical findings, including: (1) short duration of diabetes, (2) absence of diabetic retinopathy and (3) presence of microscopic hematuria.
The aim of the present study was to determine the predictors for NDRD in the patients with type 2 diabetes manifesting overt proteinuria. For this purpose, we retrospectively evaluated the relationship between clinical features and histological findings in type 2 diabetic patients who underwent renal biopsy in our hospital.
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Patients and methods
We analyzed 97 Japanese patients with type 2 diabetes who underwent renal biopsy in Okayama University Hospital (age: 52.8 ± 16.0, mean ± S.E.M., male/female: 58/39). Every case was the first visit to our department at the decision of performing renal biopsy and the cases observed for a certain period in our department or re-biopsy cases were not included. All the patients manifested overt proteinuria (>0.5 g/day). Percutaneous renal biopsy was performed in these patients after obtaining a signed
Results
Table 1 shows the clinical and laboratory findings in each group. Duration of diabetes was significantly shorter in the non-DN group than in the other two groups. There were no significant differences among the three groups in age, HbA1c, serum total protein, serum creatinine and urinary protein.
Table 2 lists the renal disease entities identified as NDRDs in the complicated group and non-DN group. IgA nephropathy (25.8%) was the most frequent NDRD in these two groups.
The duration of diabetes
Discussion
In the present study, 62 (63.9%) of 97 type 2 diabetic patients had various types of NDRD. Previous studies demonstrated that NDRD accounts for 12.2–32.7% of renal involvements in the diabetic patients [3], [4], [5], [6], [7], [8], [9], although Fioretto et al. [10] reported that there was no definable NDRD in a cohort of 34 unselected microalbuminuric patients with type 2 diabetes mellitus. The prevalence of NDRD was much higher in our study compared to the previous studies. This discrepancy
Acknowledgments
We thank Dr. Toshihide Tsuda, MD, Ph.D., Department of Social and Environmental Life Sciences/Social Medicine and Longevity Sciences Hygiene and Preventive Medicine, Okayama University Graduate School of Medicine and Dentistry, for advice on statistical analyses.
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