An 88-year-old man with a 30-year history of type 2 diabetes and a 3-year history of chronic renal failure was admitted for evaluation of anasarca. On admission, findings of nephrotic syndrome and microscopic hematuria were observed. During the course of therapy, rapid deterioration of renal function occurred with the appearance of pneumonia. Irrespective of the therapy with hemodialysis and antibiotics, he died of respiratory failure. The autopsy showed a rare case of rapidly progressive glomerulonephritis (crescentic glomerulonephritis) superimposed on membranous nephropathy. This experience highlighted the importance of the differential diagnosis of non-diabetic glomerulopathy even in elderly patients with diabetes mellitus.