Platelet aggregation in various stages of diabetic retinopathy: evaluation using the PFA-100

Background: Platelet hyperactivity has been reported in diabetic patients. Some evidence suggests that platelet hyperaggregation may participate in the pathogenesis of diabetic complications such as retinopathy.Objectives: We aimed to compare platelet aggregation (PA) in patients with type II diabetes with no apparent retinopathy (NAR), nonproliferative diabetic retinopathy (NPDR), proliferative diabetic retinopathy (PDR) patients, and healthy individuals to evaluate the possible role of PA in the pathogenesis and staging of DR.Participants and methods: Blood samples from 30 patients (10 diabetics with NAR, 10 with NPDR, and 10 with PDR) and 10 healthy individuals were assayed for PA using a platelet function analyzer-100.Results: On comparing all the studied groups in terms of the demographic, clinical, and laboratory parameters, the mean age and the duration of diabetes were significantly higher in the PDR group (P 0.001). The PDR group also showed higher levels of platelet count, glycated hemoglobin, and shorter closure time (CT) (P 0.001). Both NPDR and PDR showed higher levels of fibrinogen (P 0.001). CT was correlated inversely with the fibrinogen level in the NAR group (P=0.000) and with the duration of diabetes in the NPDR group (P=0.04). No correlation was found between CT and any of the parameters studied in the PDR group (P 0.05).Conclusion: PA is increased in the PDR stage in comparison with NAR, NPDR stages, and healthy individuals. This may provide a clue of its role in the pathogenesis and staging of DR. Also, this study highlights the crucial contribution of glycemic control and duration of diabetes in the progression of DR.