Renal affection in patients with diabetes mellitus is not always caused by diabetic nephropathy.

Accumulated clinical data suggest that non-diabetic nephropathy complicating type 1 diabetes mellitus is rare, accounting for 2-3% of unselected diabetic patients with proteinuria. In contrast, non-diabetic kidney disease is a common finding in patients with type 2 diabetes mellitus. Joint analysis of available data on prevalence of non-diabetic kidney disease among type 2 diabetic patients revealed that non-diabetic nephropathy was evident on kidney biopsy approximately in 22% of European and 26.7% of Asian patients with type 2 diabetes mellitus. Therefore, kidney biopsy may become a useful diagnostic option among proteinuric patients with type 2 diabetes mellitus. However, it is generally agreed that renal biopsy cannot be used as a routine diagnostic test in all type 2 diabetic patients with proteinuria. Diabetic subjects that may benefit form kidney biopsy should be rather identified on a case-by-case basis. Absence of diabetic retinopathy, particularly used in combination with acanthocyturia, may come useful in decisions about kidney biopsy in type 2 diabetic patients.