Q. Why does home glucose monitor show higher reading than the lab?

Answered by
Dr. Divakara. P
and medically reviewed by iCliniq medical review team.
This is a premium question & answer published on Dec 28, 2016 and last reviewed on: Feb 17, 2021

Hi doctor,

My father checked his fasting sugar in a blood glucose home monitor using blood taken from pricking the finger and then putting drops of that blood on a test strip. It came out 130 mg/dL. Then, he went to a laboratory and there he gave his blood sample. In laboratory test, the fasting sugar came out to be 108 mg/dL. What is the reason for this difference? The laboratory test was done one hour after the test on home monitor. The same thing has happened many times. Why does home monitor show higher reading than that in the laboratory?



Welcome to

  • First of all, there shall be difference in reading of blood sugars checked through glucometer and that done in the laboratory. Because, laboratory check for serum blood glucose and home monitor check for blood glucose. There is a minor difference between blood and serum.
  • Moreover, with the passage of time the blood or even serum sugar keeps decreasing unless the person eats something. So, a delay of 1 hour by itself can cause the laboratory value to come less than home monitor.
  • So, next time when you do laboratory test for your father do check from home monitor at the same time when a blood sample is drawn for laboratory testing.

For further information consult an endocrinologist online -->

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