Effect of aspirin on platelet aggregation in diabetes mellitus.

The effect of aspirin n vitro and in vivo on platelet aggregation has been studied in 13 diabetic subjects without retinopathy, 16 diabetic subjects with retinopathy and 20 age- and sex-matched control subjects. The rate, degree and duration of collagen-induced aggregation were greater in the diabetic patients (p less than 0.05; p less than 0.01; p less than 0.05). The residual aggregation in vivo was greater in all diabetic patients with aspirin, whilst it only occurred in vitro in patients without retinopathy. A decreased latent period was seen in diabetic patients, to a greater extent in those with retinopathy. Significant differences in the rate, degree and duration of arachidonic acid-induced-aggregation were also seen in patients with retinopathy treated with aspirin (p less than 0.05; p less than 0.01; p less than 0.05). Disaggregation only occurred with aspirin in vitro and was more frequently seen in normal subjects.