Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Get emergency help for severe vomiting, abdominal pain, deep or rapid breathing, confusion, unusual drowsiness, or an inability to keep fluids down.
These can occur with a serious high-glucose emergency or another acute illness and should not be attributed to prediabetes.
Chest pressure, severe shortness of breath, one-sided weakness, facial drooping, or sudden trouble speaking also requires emergency help.
Seek prompt medical assessment if you develop persistent thirst, frequent urination, blurred vision, repeated infections, unexplained weight loss, or worsening fatigue.
These symptoms may indicate that blood glucose has entered the diabetes range.
And for anyone, someone who:
Arrange a routine appointment if a blood test suggests prediabetes, if you have several risk factors, or if you are unsure when you should be tested again.
This is not usually urgent.
The article also says
Prediabetes itself is not normally an emergency.
Every sign above is quoted from the sofidex article on Prediabetes. If you are not sure, err upward — it is always reasonable to be checked.