Can you drink black coffee before a fasting blood glucose test?

Can you drink black coffee before a fasting blood glucose test?

You can check the answer of the people under the question at Quora “does coffee affect a1c test

0 thoughts on “Can you drink black coffee before a fasting blood glucose test?”

  1. The original 50g glucose tolerance test in the UK used to allow a cup of tea with milk and sugar before the test. However it’s now known that caffeine affects glucose levels and insulin response – particularly in obese patients.
    So now it’s not allowed.
    A tee years ago I had a fasting blood glucose test and absentmindedly drank a cup of tea with no sugar before the test.
    The fasting glucose was raised.
    A second test was normal.
    Caffeine ingestion before an oral glucose tolerance test impairs blood glucose management in men with type 2 diabetes.
    There are lots of other links on this subject in the abstract linked above.

  2. Usually the answer is yes, but the instructions the lab or doctor’s office gave you for the test should tell you what you can and cannot have before the test.
    If you have questions, call the lab or the doctor and see what they say.

  3. There’s a fair amount of controversy about this.
    Here’s a nice summary: Avoiding coffee before a blood test
    The LiveStrong article says to avoid it but that seems to be an opinion since no references are given: Can I Have Coffee If I’m Fasting Before Blood Work? |
    I am unable to locate any scientific studies to answer this question definitely. Sad, because it would be fairly easy to do, using each subject as their own control. But who would fund it?
    My conclusion: black coffee is unlikely to affect fasting (or non-fasting) serum glucose in a clinically meaningful way.


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