Secondary focal segmental glomerulosclerosis following kidney transplantation in a patient with type I diabetes mellitus

Although recurrent diabetic nephropathy is common in patients with type I diabetes after kidney transplantation, the development of focal segmental glomerulosclerosis (FGS) is rare, and its development generally takes several years. We report here a case of type I diabetes mellitus with secondary FGS accompanied by proteinuria 10 months following kidney transplantation. Episode biopsy showed secondary FGS, evidenced by glomerular capillary collapse and large epithelial cells with ballooning degeneration. Exudative dense deposition of IgM in a diffuse global mesangial pattern and enlarged glomerular diameters were observed, suggestive of glomerular hyperfiltration which can lead to secondary FGS. An imbalance in body size between donor and recipient and/or uncontrolled diabetes are potential causes of glomerular hyperfiltration. We administered angiotensin-converting enzyme inhibitor and angiotensin II receptor blocker to reduce hyperfiltration-induced renal damage; the combination therapy reduced proteinuria from 2346 to 258 mg/d. Secondary FGS should be a consideration after kidney transplantation in patients with type I diabetes mellitus.