Considering the increasing incidence of diabetic nephropathy and its serious complications, the prevention of nephropathy evolution risk in diabetic patients is the subject of several recently initiated studies. In diabetic patients with advanced nephropathy, the lowering of proteinuria by renin angiotensin system blockers induces an evolution risk reduction, which can be further improved by increasing the dose of angiotensin II receptor antagonist (ARA II). Such a synergy can be also obtained with the association of an ARA II and an angiotensin converting enzyme (ACE) inhibitor, provided that the diuretic dose given to the patient is increased. In terms of cardiovascular risk, diabetic patients benefit from this type of treatment, as cardiovascular events increase with the level of proteinuria. In micro-albuminuria patients, sufficient doses of ARA II or ACE inhibitors are needed to avoid relapse after treatment discontinuation. In normo-albuminuria patients also, the treatment with a renin angiotensin system blocker significantly decreases the risk of development of microalbuminuria. Thus, the reduction of proteinuria or the prevention of its appearance with renin angiotensin system blockers is the main therapeutic strategy to prevent the evolution of nephropathy in diabetic patients.