Endothelial cell activations and/or dysregulations of the coagulation system are crucial parameters for the prognosis of disease in patients with IDDM. Recent data suggest that expression of the adhesion molecules E-selectin and P-selectin are markers of endothelial cell activation and/or platelet activation and might modify immunologie responses after shedding from cell membranes. In patients with newly diagnosed IDDM only limited data on circulating selectins are available. This has prompted us to measure levels of soluble (s) forms of P-selectin and E-selectin in 18 patients with newly diagnosed IDDM and two years after the onset of insulin substitution therapy in comparison to 18 age-matched healthy control subjects. HbAlc and blood glucose levels were significantly higher in patients with new onset diabetes, compared to the same patients after two years of insulin therapy (HbAlc: 12±3% vs. 7.8±2%; p< 0.01; blood-glucose: 409±163 mg/dl vs. 131±23 mg/dl; p< 0.01), but no correlation between these metabolic parameters and soluble forms of E-and P-selectins were noted.