METABOLIC CONTROL IN INSULIN-DEPENDENT DIABETES-MELLITUS, AS REFLECTED IN THE IN-VITRO EFFECTS OF PLATELETS ON ENDOTHELIAL-CELL PROLIFERATION AND PROSTACYCLIN PRODUCTION

We tested the hypothesis that the degree of metabolic control in diabetes mellitus may be a determinant of the ability of platelets to stimulate proliferation of endothelial cells (ECs) and smooth muscle cells (SMCs). Platelets were obtained from 24 patients (two groups of 12 patients each) with insulin-dependent diabetes mellitus (IDDM) and increased blood glucose concentrations (HbAlc > 10% Hb), duration of disease 2-45 years, on no other medication than insulin at the time of blood sampling or during the preceding 6 months, and with no signs of coronary artery disease, nephropathy, hypertension or retinopathy. The patients served as their own controls, platelets being obtained from them again 2-4 months later when their mean glucose values were lower (HbAlc < 6.5% Hb). EC proliferation was significantly reduced after exposure to platelets obtained from the patients when their metabolic-control had improved, whereas no significant differences were seen in either SMC proliferation or prostacyclin production. There was no correlation between changes in insulin dosage and either cell proliferation or prostacyclin production, or between changes in lipid values and cell proliferative capacity. It is concluded that, EC proliferation will be greater, owing to the platelet effects found in vitro, when metabolic control in diabetics is poor than when it is good, which may be of importance regarding the repair of endothelial lesions.