What is the life expectancy of someone with Adrenal Insufficiency?

I'm unsure

As long as basic, sensible precautions are taken and a workable treatment plan is in place with emergency bracelets with your information for treatment in an emergency and you are stable, the morbidity is as everybody else's. However there is certainly added risk if precautions are not taken and in a case where you may be unconscious, eg. in a traffic accident, a limb is broken,or copious bleeding and the emergency services are unaware of your condition, then chances of death become very high ! Always have a bracelet or necklace with your details on and store emergency action details in a container which can be stored in the fridge, a magnetic sign can be stuck on the outside to say what is in the fridge ! I am unaware of any advances that would be available to an NHS patient, sensible precautions will be my watchword and living life as well as I am able.

Without timely diagnosis and treatment adrenal insufficiency will lead to adrenal crisis and death. Our bodies require cortisol to sustain life.
With proper diagnosis and replacement therapy our life expectancy is quite good.

Most people with AI have a normal life expectancy now. The exception is with adrenal crisis being left untreated and the mortality rate for adrenal crisis is higher in adolescents and children than adults; most likely because they lack the self awareness or ability to communicate they are in crisis.