The effect of non-specific beta-blockade on metabolic and haemostatic variables during hypoglycaemia.

Several haemostatic and metabolic variables were monitored during insulin stress tests (ISTs), which were preceded by placebo, nadolol or propranolol ingestion for 10 days. Nadolol administration blocked the rise in plasma factor VIII: RAg concentrations, but no significant changes were observed in platelet aggregation/thromboxane A2 release. Propranolol administration reduced the significance, but not the magnitude, of the plasma factor VIII:Rag rise and also marginally inhibited platelet aggregation/TXA2 release. Both nadolol and propranolol inhibited the hypokalaemia of hypoglycaemia and retarded the recovery of plasma glucose concentrations, probably by inhibiting lipolysis (as indicated by serum nonesterified fatty acid concentrations). Both nadolol and propranolol often masked and delayed the onset of the symptoms of hypoglycaemia. Beta-blockers may exert beneficial effects by modifying haemostatic variables and by preventing hypokalaemia during stressful situations, such as hypoglycaemia or myocardial infarction, both in diabetics and in non-diabetics. However, any benefit must be balanced against the risk of masking, and possibly increasing the incidence of, hypoglycaemia in diabetics.