Direct animal and indirect human evidence of altered platelet function in diabetics

All agree on altered platelet function in vitro (and increasingly in vivo) in diabetics of substantial duration and/or with clinical evidence of angiopathy. However, a platelet abnormality earlier in the disease remains uncertain. Three sets of data from Oxford will be reviewed: (1) Observations of Honour on platelet aggregation at sites of minimal injury within blood vessels of anesthetized rabbits, with greater sensitivity to superfused ADP when hyperglycemia has followed alloxan only days previously. This increased aggregatability (not hyperglycemia determined) is reversed by a few days of insulin treatment or by dipyrimadole (alone or with synergistic acetyl salicylic acid): (2) Beta-thromboglobulin is released from platelets and is increased in venesected blood from diabetics after a standardized procedure (no prostaglandin E1 in anticoagulant) with final radioimmunoassay. Results in diabetics after surgery, etc., will also be presented, and (3) in a prospective study of newly-diagnosed, mostly maturity-onset type diabetics, an increase in plasma fibrinogen (thrombin coagulation of plasma, controlled against normals) was observed during the first 3 yr, largely due to males treated with sulfonylureas; decreases in platelet count and in prothrombin concentration were also statistically significant.