At least 17 million people in the United States have diabetes mellitus, and another 50 million have hypertension. These chronic diseases increasingly coexist in our aging population. Both diseases are important predisposing factors for the development of cardiovascular disease (CVD) and renal disease, and the coexistence of these risk factors is a very powerful promoter of CVD and renal disease. There is accumulating evidence that the rigorous treatment of hypertension and other risk factors such as dyslipidemia and hyperglycemia considerably lessens the burden of CVD and renal disease in patients with diabetes mellitus. There is considerable evidence that strategies addressing diet and exercise reduce the development of diabetes and are an important component of treatment in persons who have established diabetes. There are also considerable data suggesting that the treatment strategies that interrupt the renin-angiotensin system have special benefits in patients with diabetes and may prevent the development of clinical diabetes in hypertensive patients with impaired glucose tolerance. Data from a recent study indicate that the control of systolic blood pressure, using a diuretic agent as part of antihypertensive therapy, reduces the risk of stroke and other CVD end points. Recent reports indicate that angiotensin receptor-blocking agents decrease the rate of development of proteinuria and diabetic renal disease. These observations will likely have a significant impact on treatment of hypertension in patients with type 2 diabetes mellitus.