HYPERTENSION IN PATIENTS WITH DIABETES-MELLITUS

Diabetes mellitus and hypertension each confer increased cardiovascula r risk. That risk is much greater when the diseases coexist and is fur ther magnified by their frequent association with dyslipidemia and cen tral obesity. Insulin resistance appears to be an important common com ponent to these four entities, whether or not the relationship is trul y cause and effect. Increased renal tubule absorption of sodium and in creased sympathetic nervous system stimulation from insulin have been said to be the mechanisms by which elevated levels of insulin cause hy pertension. However, animal experiments suggest that these are short-t erm effects only and that long-term insulin may actually increase peri pheral blood flow and reduce blood pressure. Experiments in humans sug gest that the insulin resistant state in obese patients and type II di abetics is associated with a decrease of the usual vasodilatory effect of insulin. Antihypertensive drugs have differing effects on insulin resistance. Angiotensin converting enzyme inhibitors, alpha-adrenergic blockers, and dihydropyridines appear to improve insulin sensitivity. Other calcium channel blockers appear to be neutral, as is furosemide . Thiazide diuretics, spironolactone, and beta-adrenergic blockers imp air insulin sensitivity. The drugs that increase insulin sensitivity a lso tend to improve dyslipidemia or remain lipid neutral. In contrast, those drugs that tend to impair insulin sensitivity also tend to wors en dyslipidemia.