Platelet aggregation and reversible platelet aggregates in type I-diabetes staged by retinal fluorescein angiography.

In 70 patients with juvenile-onset, insulin-dependent (type I) diabetes and 75 age- and sex-matched controls the reversible platelet aggregates expressed as platelet count ratio (PCR) and the ADP-induced platelet aggregation were studied. Retinal microangiopathy was staged by retinal fluorescein angiography. The mean PCR of the patients (0.82 +/- 0.02) was statistically significantly lower than that of the controls (0.97 +/- 0.01). However, in different stages of retinopathy no significantly different PCR could be observed. ADP-induced platelet aggregation (0.5 and 1.0 micromol/l) exhibited a higher reactivity of diabetic platelets, but with the exception of tangent alpha (see later), the differences were not statistically significant in comparison to the controls. After collagen-induced platelet aggregation (0.5 and 1 microgram/ml) the lag time in diabetics was significantly (p less than 0.001) lower than in the controls, whereas the other quantitative parameters exhibited higher platelet reactivity in general, though not statistically significant. No relationship between PCR and the in vitro induced aggregation was found. The degree of retinopathy had no significant influence on platelet aggregation. In general, the data demonstrate an increase in sensitivity of platelets in juvenile-onset diabetics, whereas no influence of stage of microangiopathy could be detected.