Why Are Glucose Meters Inaccurate?

A drop of blood from a fingertip can reveal your blood sugar level.

Glucose or blood sugar tests can indicate whether a person suffers from diabetes. Glucose meters, however, can give varying readings. A reading can vary by up to 20 points and still qualify as accurate.

Blood Sugar

According to the Mayo Clinic, a normal blood sugar reading, when taken between meals, ranges from 90 to 130 milligrams per deciliter.

Glucose Meters

A glucose meter allows diabetics to measure their blood sugar at home. As described by the Mayo Clinic, a drop of blood from a finger prick goes onto a test strip, which the meter then analyzes.

Margin of Error

Different glucose meters may give different readings, but according to American Diabetes Services, a reading within 20 points of laboratory test results counts as accurate.

Comparisons to Lab Tests

American Diabetes Services explains that laboratory test results usually range about 12 points higher than glucose meters because they examine blood plasma alone, while glucose meters get their results from whole blood.

Interpretation

Your glucose meter reading should equal the lab result divided by 1.12, assuming that you take both samples at the same time.

References

• Blood sugar monitoring: Why, when and how
• Choosing the right blood glucose meter
• Is Your Glucose Meter Accurate?