Insulin resistance and essential hypertension: pathophysiologic and therapeutic implications

Essential hypertension is often accompanied by metabolic abnormalities, which commonly include insulin resistance. In this paper we review data on the effects of different antihypertensive drugs on insulin resistance.

A number of reports have described a frequent association between hyperinsulinemia, hypertension and obesity. In epidemiological surveys, increased insulin concentrations have been seen in hypertensives and have been correlated with cardiovascular risk. Although the impact of antihypertensive therapy on glucose and lipid metabolism has been widely studied, few researchers have investigated the effects of different antihypertensive drugs on insulin resistance. An analysis of available data from controlled studies has shown that the use of thiazides is correlated with a decrease in insulin sensitivity. Pollare and co-workers tested insulin sensitivity by using the glucose-clamp technique in hypertensive patients, and found a 21% decrease in insulin sensitivity during atenolol treatment. Similar findings have been described with metoprolol. In contrast, calcium antagonists do not alter insulin resistance and/or sensitivity. At present, angiotensin converting enzyme (ACE) inhibitors seem to be the only drugs able to improve insulin sensitivity.

ACE inhibitors may improve insulin-dependent glucose uptake, thus leading to a reduction in insulin concentrations. Calcium antagonists appear to preserve insulin sensitivity. Since insulin resistance may be an additional risk factor for cerebral and vascular disease, these drugs may be particularly useful in insulin-resistant hypertensives.