A study of platelet-relevant parameters in patients with diabetic microangiopathy.

In 16 diabetic patients with microangiopathy, survival of 111In-labelled autologous platelets, mean platelet volume, megathrombocyte index, spontaneous and ADP-induced platelet aggregation, platelet retention, beta-thromboglobulin, von Willebrand factor and factor VIII-related antigen were measured; the splenic uptake of radioactive label was quantitated in six patients. Compared with normal subjects, increased platelet aggregation (p less than 0.01), von Willebrand factor (p less than 0.02) and factor VIII-related antigen (p less than 0.02) were observed. Platelet survival was shortened in two patients. It correlated inversely with the splenic radioactivity uptake (r = -0.95; p less than 0.01), suggesting that platelets ended their life in the spleen, not in the microcirculation. No significant relationships were found between the various tests performed, nor between these and the severity of microangiopathy or other clinical data. In spite of the evidence for altered platelet function in patients with diabetic microangiopathy, currently available tests are not specific enough to clarify the nature of these changes or their possible pathogenic significance.