The Glucomark is a pretty new test. I actually think it sounds quite promising as many diabetics have high postprandial numbers that may not be reflected in their HbA1c. It is still not really used. Samantha talked about it here (https://forum.tudiabetes.org/topics/i-found-a-keeper). You can pretty much get similar information by testing your own blood sugar after eating.
My endo regularly orders the fructosamine as I have a lot of inconsistencies between my meter readings, HbA1c and fructosamine.