Although diabetic nephropathy is a slowly progressing, well studied disease, it is the most common cause of end stage renal disease in industrialized countries. Recently the first randomized controlled long term trials about microvascular complications in patients with type 2 diabetes have been published. Only seven years ago the first hallmark papers about metabolic control and ACE inhibition emerged. This review highlights the current status of prevention and therapy of diabetic nephropathy by metabolic and blood pressure control in type 1 and type 2 diabetic patients, depending on their stage of nephropathy (normo-, micro-, or macroalbuminuria). In patients with type 1 diabetes and normo- or microalbuminuria, strict metabolic control has been shown to slow the progression of nephropathy. In macroalbuminuric patients an aggressive antihypertensive treatment, preferably with an ACE inhibitor, is more important than the metabolic control. ACE inhibitor therapy has also been proven beneficial in microalbuminuric patients, but not yet in normotensive, non-albuminuric type 1 patients. Because of the high prevalence of hypertension in patients with type 2 diabetes, a strict antihypertensive treatment is more important than metabolic control for the prevention of progression of microvascular disease. Since most patients need a combination of antihypertensive medications a recommendation for a single substance class can not be given.