Up to 75% of adults with diabetes also have hypertension, and patients with hypertension alone often show evidence of insulin resistance. Thus, hypertension and diabetes are common, intertwined conditions that share a significant overlap in underlying risk factors (including ethnicity, familial, dyslipidemia, and lifestyle determinants) and complications. These complications include microvascular and macrovascular disorders. The macrovascular complications, which are well recognized in patients with longstanding diabetes or hypertension, include coronary artery disease, myocardial infarction, stroke, congestive heart failure, and peripheral vascular disease. Although microvascular complications (retinopathy, nephropathy, and neuropathy) are conventionally linked to hyperglycemia, studies have shown that hypertension constitutes an important risk factor, especially for nephropathy. The familial predisposition to diabetes and hypertension appears to be polygenic in origin, which militates against the feasibility of a "gene therapy" approach to the control or prevention of these conditions. On the other hand, the shared lifestyle factors in the etiology of hypertension and diabetes provide ample opportunity for nonpharmacologic intervention. Thus, the initial approach to the management of both diabetes and hypertension must emphasize weight control, physical activity, and dietary modification. Interestingly, lifestyle intervention is remarkably effective in the primary prevention of diabetes and hypertension. These principles also are pertinent to the prevention of downstream macrovascular complications of the two disorders. In addition to lifestyle modification, most patients will require specific medications to achieve national treatment goals for hypertension and diabetes. Management of hyperglycemia, hypertension, dyslipidemia, and the underlying hypercoagulable and proinflammatory states requires the use of multiple medications in combination.