Thank you Isis.
Frankly, I cannot think of a way that your "weird illness," such as high blood sugar or something of the type would affect your testing results so that you tested positive for any of the eight to ten substances that are going to be screened for. They test diabetics and such people with "normal illnesses" all the time. If the problem is with say maybe, passing urine for the testing under the circumstances of the test, (can't pee in the cup, have to be catherized, have to stand on my head or lie on the floor to pass urine) I would still take my chances with the testing people and make the try before I asked for different consideration.
Remember the company makes its own policies, it's not the police state that they have to satisfy by doing this drug testing. Their management has elected to do a certain standard type of testing, they probably contract for it, and the people doing the hiring are going to be very repelled by a person who is requesting that they make some sort of exception to their normal drug testing routine for some hinky reason. They quite likely are in the first place not going to agree to accomodate such a request, and two, are going to eliminate you as a candidate for the job for asking.
They do not, remember, have to hire anyone, and they do not have to make it easy for you to be hired or make extra accomodations for something that is not a recognized limitation or condition and that you have not told them about in the first place.
Has this ever happened to you, or are you sitting around thinking of ways to get around something that isn't even an issue yet?
What I would do is go ahead and take the test when offered an opportunity to do so as a prerequisite for hiring. If it showed that I had failed the test, which I am interested in whether it would or not, if this is really a condition or illness you have and not a devotion to medicinal weed, then at that point you could do some 'splaining and ask them to give you the hair or follicle test. Whether or not they would would depend on whether or not you were a really really excellent candidate and they really really wanted you otherwise.
But asking for an exception
before the test does nothing but indicate a possible expectation of a problem, in other words, I like to smoke dope, can you give me a test I have a better chance of cooking? I hate to waste time with the regular old urinalysis. Conditions like a nervous bladder or needle phobia (remember that one, gang?) do not have a lot of credibility.