Can one have normal sugar level in blood but high sugar in urine?

Answer by Dr. Albana Greca, MD, MMedSc

Hello,

I read your question carefully. In most healthy people, urine usually contains little or no glucose. When glucose is found in the urine, the first thing doctors usually check is whether blood sugar has been high.

Why Sugar Can Appear in Urine

The kidneys filter glucose from the blood and usually return it back to the bloodstream. If blood sugar becomes too high, the kidneys may not be able to reabsorb all of it, so glucose spills into the urine.

This is why urine glucose can be seen in uncontrolled diabetes, after very high post-meal blood sugar, or when blood sugar has been high earlier but is normal at the time of the blood test.

You may find this useful: diabetes urine test.

Can Blood Sugar Be Normal but Urine Sugar High?

Yes. This can happen in several situations:

• Renal glycosuria: the kidneys release glucose into the urine even when blood glucose is normal.


• Timing difference: blood sugar may have been high earlier, but normal when the blood sample was taken.


• Pregnancy: urine glucose may appear more easily, but gestational diabetes still needs to be ruled out.


• Medicines: SGLT2 inhibitor diabetes medicines are designed to make the kidneys pass glucose into urine.


• Kidney tubular problems: some kidney conditions affect glucose reabsorption.


• A false-positive or testing error is also possible, so repeat testing may be needed.

Does This Mean Diabetes?

Not always. Sugar in the urine can be a clue, but diabetes is diagnosed mainly with blood tests, not urine alone.

Your doctor may review:

• Fasting blood glucose


• HbA1c


• Random blood glucose if symptoms are present


• Oral glucose tolerance test if needed


• Kidney function and urine tests

Read more here: blood tests for diabetes and blood glucose tolerance test.

What If This Happens in a Child?

If a child has repeated sugar in the urine but normal blood sugar, normal kidney function, normal ultrasound, and a normal glucose tolerance test, one possible explanation is renal glycosuria. This can be benign in some cases, but the child should still be followed by a pediatrician, and sometimes a pediatric endocrinologist or kidney specialist.

The doctor may want to monitor growth, hydration, urine results, electrolytes, kidney function, and symptoms over time.

You may also find this page useful: children’s blood sugar levels.

When to Call the Doctor

Please contact your doctor if urine glucose is repeated or if you have:

• Frequent urination or excessive thirst


• Unexplained weight loss


• Tiredness, weakness, or dehydration


• Blurred vision


• Recurrent urinary or yeast infections


• Ketones in the urine or blood

Related Questions

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