Hypertension and diabetes mellitus are common diseases in the United States. Patients with diabetes have a much higher rate of hypertension than would be expected in the general population. Regardless of the antihypertensive agent used, a reduction in blood pressure helps to prevent diabetic complications. Barring contraindications, angiotensin-converting enzyme inhibitors are considered first-line therapy in patients with diabetes and hypertension because of their well-established renal protective effects. Calcium channel blockers, low-dose diuretics, beta blockers, and alpha blockers have also been studied in this group. Most diabetic patients with hypertension require combination therapy to achieve optimal blood pressure goals.