Diabetic Nephropathy is the most common cause of end stage renal disease in Western countries. An increased urinary albumin excretion represents a characteristic sign of diabetic kidney damage. Regular screening for microalbuminuria allows early detection and timely intervention. In overt diabetic nephropathy, quantification of albuminuria helps monitoring disease progression. Therapeutic interventions to reduce albuminuria retard progression of nephropathy and reduce cardiovacular mortality, since albuminuria represents an independent cardiovascular risk factor. This review article describes the natural history of diabetic nephropathy and discusses practical issues for the measurement of albuminuria. Available prophylactic and therapeutic measures, particularly glycemic control and inhibition of the renin-angiotensin-aldosteron system, are reviewed using an evidence based approach.