Circulating platelet-leukocyte aggregates: A marker of microvascular injury in diabetic patients

Diabetes is associated with multiple disorders including metabolic, cellular and blood disturbances leading to vascular complications. Increased circulating levels of platelet-leukocyte aggregates (PLA) have been described in several thrombotic diseases. In this study, we have evaluated circulating PLA in diabetic patients and we have investigated whether they may be a marker of vascular complications. Using flow cytometry assay, we have quantified PLA percentages in 65 diabetics including 20 patients with type I and 45 with type II diabetes, and 25 healthy subjects. Specific labelling identified platelet-polymorphonuclear aggregates (PPA) and platelet-monocyte aggregates (PMA). We have observed a significant increase of PPA and PMA levels in diabetics (22 +/- 12% and 45 18%, respectively) compared to controls (7 +/- 4% and 19 +/- 10%, respectively) (p < 0.01). However, both PPA and PMA values were similar in the two diabetes types. Circulating PPA and PMA were significantly enhanced in diabetics with vascular lesions (PPA: 24 +/- 13%; PMA: 50 18%) than in diabetics without vascular lesions (PPA: 18 +/- 8%; PMA: 38 +/- 15%) (p < 0.05 and p < 0.01). Patients with PPA > 18% and/or PMA > 38% showed a more important vascular injury (OR: 6; 95% CI: 1.6-23). Increased PMA circulating rate is particularly correlated to retinopathic injury (OR: 19; 95% CI: 2.3-154).