Chronic renal failure is usually a silent disease until its late stage, especially in elderly people. Screening for such disease is particularly useful in hypertensive diabetic patients above 50 years. The causes are indeed often vascular or metabolic (directly or not directly linked to diabetes mellitus). Other less frequent causes are yet possible. The search for the right diagnosis of renal insufficiency is always requested to apply the appropriate treatment, combined with medical measures for secondary and tertiary prevention. This review will give general advices to avoid the development of renal disease (stages 3 and 4) or its progression, and also insist on the potential nephrotoxic effects of some drugs.