How does RhoGAM shot affect glucose levels?

Google search says RhoGAM can cause false results with glucose test, but not how.

So... I had my blood drawn to confirm my negative factor and had to drink the sugar drink at that time. Went to the next department over to get the RhoGAM shot while the drink was processing, then returned to the quick draw within about 20-30 minutes after the shot to have the blood draw for glucose levels.

Come to find out I bombed the glucose test... 202, so they said to go see an endocrinologist, which I did yesterday. I told him I'd had a few chocolates that morning (because I was starving and that was all I had to eat at work) and he said it shouldn't have been so bad on my levels... I probably hadn't eaten much the night before but I really don't remember, all the testing and stuff was after noon. I didn't think to mention the RhoGAM since it wasn't until this morning that I wondered if it could make a difference then saw that it maybe could.

I was given a glucose monitor and told to test 4 times a day. I've only tested twice so far, but my levels have been WELL under where they should be... I was at 95 after eating normally for me (target under 145) and 70 this morning (target under 85). I have never failed a urine glucose test nor did I have any problems with the sugar drink. One uncle with diabetes and never any problems myself.

Obviously I'll keep testing my levels but I'm very suspicious about what happened to cause my levels to be more than double what I've read at home so far. I'm going to keep testing this weekend then call on Monday to ask WTF if I'm still low. Any insight? 😕