 As insulin lowers the level of glucose in the blood, if too much of it is present in the circulation this can quickly lead to lowered blood glucose levels, commonly known as low blood sugar (or hypoglycemia); which as a consequence negatively affects the functioning of the brain and central nervous system.This can be rapidly and irreversibly fatal if not recognised and treated early enough.At Stepping Hill it was suspected that, due to the increased levels of insulin in the patients' bloodstreams, they quickly became hypoglycemic and three confirmed fatalities occurred.