The presence of microalbumin in the urine of persons with type 2 diabetes is perhaps the most important early signal heralding the onset of systemic vasculopathy and associated target organ damage to the brain, the heart, and the kidneys. It is easily measured and, unfortunately, frequently overlooked as a screening tool in clinical medicine. If present, it identifies patients at risk for early cardiovascular death and progressive renal disease. Microalbuminuria also identifies patients who need more rigorous cardiovascular risk management, especially more intensive blood pressure control, preferably below 130/80 mm Hg, and strict attention to glycemic control and lipid levels. Therapeutic strategies to facilitate better blood pressure control and reduce microalbuminuria likely will prove to be the most effective way to retard not only the progression of renal disease but also cardiovascular disease. Consequently, the identification and normalization of urine microalbumin excretion should be an important consideration in patients with diabetes.