Rare diagnosis in a patient with diabetes with nephrotic proteinuria.

We report a 63-year-old man with well-controlled type 2 diabetes mellitus and hypertension, who presented with new onset nephrotic proteinuria and rapid deterioration in renal function. The atypical clinical presentation prompted us to consider a non-diabetic and non-hypertensive cause and to perform a renal biopsy. A diagnosis of fibrillarglomerulonephritis (FGn) was made based on electronic microscopy. Proteinuria remained in nephrotic range despite treatment with prednisolone, and renal function deteriorated. We suggest that other causes of proteinuria should be considered in patients with diabetes who present with the nephrotic syndrome when there is no other evidence of microvascular disease. We review the spectrum of fibrillar glomerulopathies including FGn, primary and secondary amyloidosis and immunotactoid glomerulonephritis.