Do Red Blood Cells (erythrocytes) take up glucose?

I don't think RBC's take up glucose
they dont have any nucleus, so that the transport of O2 is very efficient to the tissues, and not even the smallest part of it is taken up by RBCs themselves, any cell would require O2 to burn the glucose, if they dont even take up O2 what good is glucose?

I am a Molecular and Cellular Biology Graduate, so there is your source. RBC's only transfer Oxygen, that is there function, but do they have mitochondria, that is your question- if they do, then they take up glucose, if not glucose wouldn't do any thing for them. It is true they have no nucleus, but they are a cell just like all other cells in the body, would you think they need energy? If they do, why did your experiment not work. Maybe you would have to starve the RBC before you subjected them to glucose or change the molar concentration of your substrate. I know i didn't answer your question, but think about it.

An RBC is a cell
all cells are "living"
all life requires metabolism
a red cell has metabolism
metabolism requires glucose and oxygen

-----THEREFORE-----

RBC's take up glucose

As to why your experiment failed, well that my friend was a failure in the design of the experiment. I can envision several things you might have done wrong, but I leave that for you to figure out.

Glycosylated hemoglobin is measured to indicate a patients average blood glucose concentration over the life span of the RBC (90days).  Yes. Glucose is taken up by RBC . Check the references for glycohemoglobin.

A mature rbc does not have a nucleus, or any cellular organells, this is why the cell is so short lived. But it is a living cell that carries oxygen and some carbon dioxide, it does not use the oxygen it carries for its own energy supply, the cell derives its energy anaerobically. It undergoes glycolysis, or the splitting of glucose, it works but is not very efficient. So the the answer is YES they utilize glucose and must take it in the cell.

RBC's are very unusual cells indeed.  They build every thing they need before they carry out the function we know them best for: oxygenation.  This includes the functions involving glucose uptake and its utilization.

Yes, they take up glucose, their metabolism is via glycolysis of glucose (or lactate). Uptake of glucose in rbcs is not facilitated by insulin