When I was 13weeks, my dr.(private) did the antenatal test for me, which included random glucose, ABO/Rh, CBC (haemoglobin, etc), Hep B Ag/Ab, Rubella, VDRL, CMV Ab. my phone report was, everything alright but glucose (which is 8.0). so, I was suggested to do the glucose tolerance test (OGTT). That glucose drink was better than what I've been told.
So, I think if you are 24 weeks already, you must have some blood test done already.. and your dr. should know everything but just not discussed with you about the results.