Evidence for a therapeutic effect of dl-propranolol in benign and malignant insulinoma: report of three cases.

Two patients suffering from benign and one patient suffering from malignant insulinoma experienced frequent incapacitating hypoglycemic attacks which did not respond to treatment with streptozotocin, diazoxide and/or diphenylhydantoin. Dl-propranolol, in dosages ranging from 30-240 mg/day, successfully abolished the symptoms of hypoglycemia, prevented recurrent hypoglycemic attacks, and normalized blood glucose levels concomitant with a reduction in pulse rate to 60/min. The main mechanism of the drug's effect seems to be the suppression of insulin release. However, other mechanisms may be involved such as increased peripheral insulin resistance. No side effects of treatment with dl-propranolol were noted. In patients suffering from insulinoma who are refractory to other forms of treatment, and for those who need symptomatic relief before surgery, dl-propranolol may play an important therapeutic role.