Interesting,
Just over 2 years ago when I was on Lantus, I also had this test. Hoped it might explain the probs I was having, but the test was negative, no Addisons. What probs are you having that' have led to you been referred for this test?
My advice would be to get off Lantus, for many people it can cause horrendous side-effects, these can be accumulitive-meaning they can take time to display themselves and often mistaken for other illnesses.
Side-effects range from anxiety, joint pain and generalised malaise to debilitating exhaustion. Some people, like myself, liken it feeling like they're being poisoned.
I am now educating my diabetes clinic, who r finally taking notice that the problems I bombarded them with for 4 years were a direct result of Lantus-Hallelujah!
Jus