How can you tell if you are hyperglycemic?

Blood test: The only way to tell if your blood sugar is high is to have the blood tested. This can be done by a blood sample sent to a lab or by the use of a blood glucose monitor by someone familiar with its use.

See below : Short of confirming with a blood sugar measurement, signs and symptoms include increased thirst, increased hunger, frequent urination, blurred vision, vomiting, or fatigue. If *very* high levels of blood sugar (> 350 mg/dL) are present for an extended period of time, confusion, stupor, and coma may occur. At that point, it would be considered medical emergency and may be life-threatening.