Microvascular Alterations in Diabetes: Focus on Small Resistance Arteries

Abstract

Diabetes mellitus is associated with high morbidity and poor prognosis because of macrovascular and microvascular complications. Alteration in microvessels may contribute to organ damage and mortality. Different to essential hypertensive patients, who present eutrophic remodelling of small resistance arteries with increased media-to-lumen ratio without net cell growth, in diabetic patients hypertrophic remodelling of small arteries occurs, which appears more difficult to be reverted. Indices of small resistance artery structure, such as the tunica media to internal lumen ratio, may have a strong prognostic significance in hypertensive and diabetic patients, over and above all other known cardiovascular risk factors. In addition, hypertrophic remodelling seems to be associated with worst prognosis. Endothelial dysfunction may be also detected in small resistance arteries from diabetic normotensive or hypertensive patients. Altered metabolic control and several other pathological mechanisms may contribute to microvascular structural changes as well as to endothelial dysfunction in diabetes. Importantly, some drugs, mainly those blocking the renin–angiotensin system (angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers), seem to be able to regress alterations of microvascular structure and therefore may be useful in preventing and/or reducing the development of organ damage and clinical events frequently observed in patients with diabetes mellitus.