Considering the role played by platelets and leucocytes in diabetic disease and keeping in mind the strong correlation between functional and metabolic aspects that characterizes this clinical condition, we evaluated, in two groups of diabetics, respectively the platelet and polymorphonuclear (PMN) cytosolic Ca2+ content (employing the fluorescent probe Fura 2-AM) and membrane fluidity (using the fluorescent probe TMA-DPH and considering the fluorescence polarization degree, inversely related to the membrane fluidity). From the obtained results, it is evident that the platelet cytosolic Ca2+ content does not distinguish normals from diabetics of type 1 and 2; the platelet membrane fluidity instead does not discriminate normals from diabetics, but differentiates diabetics of type 1 and 2 (type 1 = 0.284 +/- 0.015; type 2 = 0.314 +/- 0.018; p < 0.001). PMN cytosolic Ca2+ content and membrane fluidity do not discriminate normals from diabetics. In the two groups of diabetics none of the platelet and PMN parameters (cytosolic Ca2+ content and membrane fluidity) are related to the glycometabolic pattern.