Approximately 11 million Americans have both hypertension and diabetes mellitus. This double diagnosis places such patients at high risk for renal damage, especially end-stage renal disease. The sixth report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommends a blood pressure goal of less than 130/85 mm Hg to reduce or slow the onset of renal disease and cardiovascular events in patients with hypertension and diabetes mellitus. Recent data, however, now suggest that an even lower diastolic blood pressure goal (ie, <80 mm Hg) may be necessary. Studies have shown that use of angiotensin-converting enzyme inhibitors can prevent the progression of microalbuminuria to overt proteinuria, reduce proteinuria in patients with overt diabetic nephropathy, slow the deterioration of the glomerular filtration rate, delay progression to end-stage renal disease, and lower blood pressure. Thus, all diabetic patients with blood pressure greater than 130/80 mm Hg should begin angiotensin-converting enzyme inhibitor treatment and be titrated to moderate or high doses until the blood pressure goal is achieved. However, monotherapy still may not control blood pressure to the recommended target. Studies have shown that use of multiple antihypertensive agents is necessary and successful in helping patients reach their target blood pressure, and this may offer more renoprotection than one agent used singly. A case study that applies these concepts in outpatient practice is included.