My (probably overly critical opinion) is that if you only want to know if your bg is going over 180, you should go back to 1982 and buy some testape for urine sugar testing. Because the threshold for spilling sugar in urine is around 180.
Home bg testing is so much more important and effective than urine testing, or the glycomark test, ever was or will ever be. If your postprandial numbers are over 180 the way to find that out, is with a bg test.
I lived with urine testing and never being able to know if my bg was 40 or 80 or 120 or 170, because I didn't spill until 180. It sucked. It sucked big time. Home bg testing is way way better.
I think that docs, especially for patients who do not do home bg monitoring, may find some value in glycomark test for undiagnosed diabetics, or for "borderline" (whatever borderline means, it's a poor term) diabetics who refuse to test at home.