Background: Studies have found that certain genetic variations leaves a subject with type 1 diabetes more prone to hypoglycaemia. It it thought to be a decline in cognition during hypoglycaemia that leaves them at risk of severe hypoglycaemia. The idea is tha when you suppress the genetic phenotype with a well known antihypertensive drug an improvement in cognition will occur and this will remove the patients tendency to severe hypoglycaemia.