Causes of Varying Blood Glucose Readings

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Causes of Varying Blood Glucose Readings

Question:

I tested my glucose one morning and it was higher than I thought it should be so I tested it again on a different finger and it was lower. Why is there a difference depending on the finger you use?

Answer

A different reading from one finger to another is most likely due to an error in the way you test.

Not putting enough blood on the test strip can cause an inaccurate reading. You can also get a bad reading if the blood sample is off-center.

Not washing and drying your hands thoroughly can also give an inaccurate reading.

Substances on your skin can change your reading if they contain sugar or any material that speeds or slows the chemical reaction used to detect glucose in your drop of blood.

It is also possible that a substance could affect the color or electrical charge in your test strip sample and change your meter's reading.

Mary Pickett, M.D., is a lecturer for Harvard Medical School and an assistant professor of medicine at Oregon Health & Science University in Portland, OR. At OHSU, she practices general internal medicine and teaches medical residents and students.

Last updated:	July 20, 2009