Is there a specific suffix for "within a cell"? i.e. in a similar manner to how -aemia refers to within the blood
"Cyto"/"cytic" and similar are common prefixes/suffixes to refer to things associated with cells; however they don't necessarily specify intracellular space, they are more often referring to specific cell populations, counts, etc.

The word "intracellular" is, however, commonly used terminology for "inside the cell."

For the specific case you mention, I would simply write "high/elevated intracellular glucose" - I am unaware of any reference that uses a individual word for the same meaning. Some others have referred to "intracellular hyperglycemia" which may be a bit odd since the -emia refers to the blood, but they are specifically referring to the case where high intracellular glucose is a direct consequence of overall hyperglycemia.