Nephropathy is the major life-threatening complication of type 1 diabetes. It is due to the adverse effects of glucose-induced preglomerular vasodilation on glomerular hemodynamics. Glomerulosclerosis is initiated early in the course of diabetic nephropathy by exacerbated expression of cytokines like tumor growth factor beta1. Not all type 1 diabetes patients are at risk of nephropathy, probably because some polymorphisms in the various factors involved in its pathogenesis can modulate the course of this disease from one individual to another. Blocking the course of nephropathy by blockers of the renin-angiotensin system relies on solid pathophysiological hypotheses and has proved to be efficacious for improving the prognosis of type 1 diabetes nephropathy.