Urine Glucose (GLU) — Sugar in Urine

What is urine glucose

Urine glucose (GLU) is the amount of sugar detected in a urine test. Normally, the kidneys filter glucose from the blood and return it to the bloodstream, so a healthy person's urine should contain no glucose or only a minimal amount. When blood sugar levels exceed the so-called renal threshold (typically around 10 mmol/L or 180 mg/dL), the kidneys can no longer reabsorb all the glucose and some of it passes into the urine. This test is part of a standard urine dipstick test.

Normal range

Urine glucose is normal when it is negative (not detected) or very low. A normal result is 0 mg/dL or below the detection limit.

Why urine glucose may be elevated

The most common cause is elevated blood sugar. This may be related to diabetes mellitus (type 1 or type 2), a pre-diabetic condition, gestational diabetes during pregnancy, or after consuming a very large carbohydrate-rich meal. Less commonly, urine glucose appears due to impaired renal tubular function (renal glucosuria), where the kidneys fail to reabsorb glucose efficiently despite normal blood sugar levels. Some medications, such as SGLT2 inhibitors (used to treat diabetes), deliberately promote glucose excretion through the urine.

Why urine glucose may be low

A negative or zero urine glucose result is normal and indicates that the kidneys are efficiently reabsorbing glucose from the filtered blood. This is a good sign.

What to do next

If glucose is detected in the urine, the most important step is to check fasting blood glucose and HbA1c levels. If blood glucose and HbA1c are normal but glucose is still detected in the urine, a doctor may evaluate kidney function (creatinine, eGFR).

Monitoring over time

For people with diabetes, a urine test can be an additional home monitoring tool, but blood glucose and HbA1c tests are more accurate and informative. Regular urine testing can help detect changes early.

Questions for your doctor

1. Should I check blood glucose and HbA1c if glucose was found in my urine? 2. Could my medications explain the glucose in my urine? 3. Do I need to check kidney function? 4. How often should I repeat this test? 5. Could this be related to diabetes risk?

*This article is for informational purposes only and does not replace professional medical advice. Always consult your doctor regarding your test results.*