P-selectin, E-selectin, and mean platelet volume are markers associated with platelet reactivity that have been demonstrated to be increased in diabetes. We were particularly interested to see if there was a difference in mean platelet volume and selectins between diabetics and nondiabetics, and in diabetics with and without nephropathy, and whether there was a correlation between mean platelet volume and selectins. One hundred and fourteen diabetic patients and 31 healthy controls were investigated. Plasma levels of P-selectin and E-selectin were higher in the diabetic group than in controls (P =.001 and P =.007, respectively) and in diabetic patients with proteinuria than in patients without proteinuria (P =.002 and P =.004, respectively). Protein excretion was lower in patients with low mean platelet volume values (P =.004). In conclusion, elevated platelet volume and high selectin values may play a role in the development of vasculopathies and complications in diabetes mellitus. Further studies are needed to prove these results. © 2007 Sage Publications.