Renal pathology in type 2 diabetes mellitus: clinico-morphological correlations and grounds for biopsy

Abstract

Diabetic nephropathy (DN) is currently recognized as one of the main causes of CKD. In vast majority of patients the diagnosis of DN is based on clinical data and labs, however, in some cases pathology diagnostics is strictly needed. We studied retrospectively 103 kidney biopsies, performed in patients with type 2 DM. Indications for kidney biopsy were defined as any clinical data, suggestive for non-diabetic kidney disease in patients with DM type 2. Based on pathology findings we were able to distinguish 3 groups of patients: Group 1 (n=52) with kidney lesions, completely consistent with DN; Group 2 (n=23), showing combination of DN and kidney lesions of non-diabetic origin; and Group 3 (n=28), demonstrating the absence of DN and showing features different non-diabetic kidney diseases. The most often findings of non-diabetic lesions turned to be FSGS, IgAN, MN, crescentic GN and MCD. Neither demographic nor main clinical and lab data had no difference between the groups. We also did not found any association between the duration of DM and the type of kidney damage. In our study the most often indications for biopsy were sudden onset of NS or proteinuria in patients with relatively short duration of DM; renal failure or rapid decline of kidney function, microhematuria or the need of differential diagnostics with systemic diseases. Despite of atypical clinical presentation in those cases, about a half of these patients showed only DN by pathology. More characteristic for DN may be considered the combination of NS and impaired kidney function. Mild microhaematuria do not exclude the possible diagnosis of DN. NS with intact kidney function, as well as marked haematuria or rapidly declining kidney function in the absence of NS strictly demand pathology evaluation to rule out non-diabetic origin.