The association of hypertension and diabetes: prevalence, cardiovascular risk and protection by blood pressure reduction.

Diabetes and hypertension frequently coexist, and their combination provides additive increases in the risk of life-threatening cardiovascular events. Recent guidelines agree on the need for early, aggressive reduction of blood pressure, with a goal of <130/80 mmHg, in patients with diabetes. The mechanism that underpins the increased sensitivity of diabetic subjects to hypertension is not known, but may involve impaired autoregulation or attenuated nocturnal decrease of blood pressure. All classes of antihypertensive agents are effective in reducing blood pressure in diabetic subjects, and all show evidence of a concomitant reduction in cardiovascular risk. Although there is some evidence that agents that interrupt the renin-angiotensin system (RAS) provide greater protective effects, the data are not conclusive. However, most diabetic subjects will require combination therapy to reach goal blood pressure. Antihypertensive drugs can also significantly influence the probability that otherwise healthy individuals will develop metabolic syndrome or type 2 diabetes. While diuretics and betablockers have a prodiabetic effect, angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers may prevent diabetes more effectively than the metabolically neutral calcium channel blockers. Given that diabetes is an important cardiovascular risk factor, there is the potential for reductions in risk due to reduced blood pressure to be offset by an increased risk due to the development of diabetes. Such concerns should be considered in the selection of antihypertensive therapy.