Diabetes and hypertension.

Hypertension is about twice as common in diabetics as in non-diabetics. The increased prevalence may relate to insulin resistance and its sequelae. Hypertension is a major risk factor for both large and small vessel disease, contributing to accelerated atherogenesis and progression of diabetic nephropathy and retinopathy. Treating raised blood pressure in diabetics is beneficial in the context of large vessel disease and in slowing progression of overt nephropathy. There is controversy as to whether antihypertensives, and particularly ACE inhibitor drugs, will prevent progression from incipient to overt nephropathy. All the major classes of antihypertensives can be used in diabetics, but the thiazide diuretics and beta-blockers have metabolic side-effects which make them less appropriate as first line agents. The calcium antagonists and ACE inhibitors have better metabolic profiles and the latter reduce insulin resistance. ACE inhibitors may also have a renal protective effect in incipient nephropathy although the studies have been fairly short-term and with small patient numbers. Although ACE inhibitors and calcium antagonists are suitable as first line antihypertensives in diabetics, evidence is still lacking that these drugs reduce morbidity and mortality over and above that seen with other antihypertensives.