PLATELET ACTIVATION IN DIABETIC MICROANGIOPATHY

Platelet activation and hyperreactivity are known to be associated wit h a rapid development and progression of diabetic angiopathy, The pres ent study attempts to clarify whether IDDM patients without diabetic c omplications have an increased platelet activation and whether in vivo platelet activation is altered in the presence of diabetic microangio pathy, Platelet activation was assessed by flow cytometry analysis in 50 healthy controls (c) and in 41 patients with insulin-dependent diab etes mellitus (IDDM type 1) who were screened for diabetic complicatio ns. Sixteen of these patients (0) showed no evidence of microangiopath ic organ lesions as assessed by an established standard battery of cli nical tests, whereas the other 25 patients had diabetes derived microv ascular complications (dmc), Patients with macroangiopathy were ruled out. Platelet activation was evaluated by flow cytometric detection of four activation-dependent platelet surface markers (lysosomal GP53, t hrombospondin, P-selectin and ligand-induced binding site-1 of GPIIb-I IIa), A higher percentage of thrombospondin-positive platelets was det ected in the IDDM patients without complications: 8.6 +/- 0.9% (0) vs 6.1 +/- 0.4% (c) vs 5.4 +/- 0.4% (dmc), P < 0.05, respectively. A decr ease in GP53-, P-selectin-, and LIBS-1-positive platelets was observed in the IDDM group with dmc: for GP53 17.4 +/- 1.0% (dmc) vs 23.4 +/- 1.0% (c), P < 0.05; for P-selectin 5.5 +/- 0.6% (dmc) vs 8.0+/-0.7% (c ), P < 0.01 and for LIBS-1 8.3 + 0.9% (dmc) vs 15.8 +/- 1.3% (c), P < 0,01, No differences in these markers were found in controls and IDDM patients without complications. In addition, no correlations were foun d between the glucose metabolism and platelet activation. These findin gs indicate (i) that the platelet system is pre-activated in IDDM, and (ii) that an increased consumption of activated platelet may occur in the vessels of IDDM patients with diabetic microangiopathy.