Platelet aggregation during the first year of diabetes in childhood.

Platelet aggregability in 24 newly diagnosed diabetic children was investigated on five occasions from onset of the disease until one year after diagnosis. Twenty healthy children of similar age and sex served as controls. The magnitude of the platelet shape change after adenosine diphosphate (ADP) stimulation was decreased in diabetic children on admission (p less than 0.05) in comparison with controls, but normalized during the year of the study. Maximal aggregation and initial rate of aggregation after ADP stimulation did not change significantly during the study year, and did not differ from those in controls. Aggregation by low dose collagen (0.5 and 1.0 mg/l) increased significantly (maximal aggregation, p less than 0.01; aggregation velocity, p less than 0.001) in the diabetics during the first year after admission from seemingly normal to clearly supranormal. Aggregation induced by high-dose collagen (5.5 mg/l) remained unchanged during the observation period and did not differ from that in the control group. No correlations were found between the indicators of platelet aggregation and those of carbohydrate control at any time after diagnosis. Platelet dysfunction is thus present already during the first year of diabetes. The different time course of the ADP-induced platelet shape change and collagen-induced aggregation imply that the mechanisms underlying the abnormalities of these two platelet functions differ.