Glucose is normally reabsorbed by the kidneys and not present in urine.
When blood glucose exceeds the renal threshold (~180 mg/dL), glucose spills into urine (glycosuria).
The RUS test checks for glucose at any time of the day, regardless of meals.
Clinical uses include:
Screening for diabetes mellitus.
Monitoring glycemic status in known diabetics.
Detecting renal threshold abnormalities.
Less sensitive than blood glucose tests, but useful in basic screening and follow‑up.