I have a different glucose monitor than my brother-in-law and have been using both. However, my monitor always reads 16-20 mg/dl [0.8-1.1 mmol/L] points higher than my brother-in-law’s. When mine reads 93 mg/dl [5.3 mmol/L] (normal), his reads 77 mg/dl [4.3 mmol/L] (low). How do I know which is correct?

Both of the meters you named give plasma results, not whole blood, so that should result in values should be within about 10% of each other. Your differences are about 16% or more, which might be due to a problem with the meter or problem with using the meter. I assume the correct technique is being followed with each meter and the strips are not expired. Also, I hope one of the meters has not sat in a hot car for a while.

There could actually be many reasons for the variations, so I would suggest you take both of the machines into your diabetes educator’s office and discuss this with him/her. I certainly understand your concern.

LSF