Platelets and diabetic vascular disease

: Tests of platelet behaviour in vitro, particularly aggregation and retention and in vivo tests such as measurement of platelet survival and plasma levels of beta-thromboglobulin are frequently abnormal in diabetic patients, particularly in those with vascular disease. The concept has therefore arisen that platelet hyper-reactivity is one factor responsible for diabetic microangiopathy. Whereas there is experimental and histological evidence for the mediation of platelets in the pathogenesis of atherosclerosis, direct evidence of platelet involvement in microangiopathy is scanty. Similar alterations in platelet behaviour have been observed in a variety of other conditions with vessel wall damage in common and evidence is presented which suggests that these platelet abnormalities may be secondary to vessel wall injury. In diabetic subjects, some changes in platelet behaviour are reversed by improved glycaemic control. Evidence that platelets are involved in the pathogenesis of diabetic microangiopathy therefore remains circumstantial, though current trials of anti-platelet agents may enable a more precise evaluation of their role.