Study of the effect of metformin on platelet aggregation in insulin-dependent diabetics.

The role of metformin on platelet aggregation was studied in subjects affected by relatively well controlled type 1 diabetes. 1700 mg of metformin were added to their usual daily treatment; nothing else was changed. Patients were trained to monitor their own glycaemia and presence of degenerative retinopathy was proved. Before the administration of metformin and on day 21, the platelet induced by 1.25, 2.5 and 5 mumol of ADP and by collagen was studied. Fibrinogen, cholesterol, triglycerides, glycosylated haemoglobin and mean blood glucose levels did not show any significant modification after treatment but the maximum aggregation induced by ADP was significantly decreased; the inhibition of aggregation was particularly sensitive for low doses of ADP. No significant correlation was found between the variations in metabolism data and the reduction of the amplitude of platelet aggregation. Metformin, added to the usual treatment undergone by a diabetic treated with insulin, seems to affect platelet aggregation independently of other metabolic factors.