Patients with diabetes mellitus have an increased prevalence of hypertension and its vascular consequences, including coronary and cerebrovascular disease. Drug treatment of hypertension in diabetic subjects is fraught with potential difficulties, including the altered efficacy of medications, the increased risk of side effects, and the possibility of worsening glycemic control and increasing serum lipid levels. Despite these difficulties, treatment is an important part of reducing morbidity and mortality from vascular events. Antihypertensive therapy may also have the potential to prevent or retard the development of diabetic nephropathy. In this article, we discuss the efficacy and metabolic and nonmetabolic side effects of the various classes of antihypertensive agents in patients with diabetes mellitus and suggest a stepped-care approach to the drug treatment of patients with hypertension and diabetes.