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A1C and fasting glucose do not match

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lorib642
lorib642 Posts: 1,942 Member
in Social Groups
My fasting glucose at home runs around in the 120s. Sometimes it is 110 sometimes 140, but usually around 125. My last blood test fasting glucose 136 a1C 5.5 later in the day, after i have been moving around it goes down to about 115. I take metformin in the morning and evening.

The only other out of range result is I am slightly anemic hgb 11.7 hematocrit 34%

I don't know why I am anemic. My dr told me to I need more iron so I am taking a supplement and eating more iron rich foods.

I google A1C and anemia and I get it can falsely lower then I read and iron defciency anemia could make it higher. Does anyone know what is right?

I see an endocrinologist in a few weeks and I am sure she can tell me more, but I was wondering if anyone has any insight.

I have increased exercise and now I need to make better food choices.

My husband is on board with me to decrease carbs and we are starting to do that.

Replies

  • chelny
    chelny Posts: 179 Member
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    I don't know about the anemia. The A1C test gives an average of your blood glucose over the past 8-12 weeks. Blood glucose test gives your glucose at one point in time. A1C at 5.5 is an average blood glucose of 111. With only looking at the numbers you gave, it does seem like your A1C is low compared to the fasting glucose test numbers on a daily basis. Especially considering that your post-meal blood glucose would be higher than a fasting blood glucose, if you tested that. Interesting.
  • Dreamyriver
    Dreamyriver Posts: 91 Member
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    chelny wrote: »
    With only looking at the numbers you gave, it does seem like your A1C is low compared to the fasting glucose test numbers on a daily basis. Especially considering that your post-meal blood glucose would be higher than a fasting blood glucose, if you tested that. Interesting.

    Post meal blood glucose isn't necessarily higher than fasting (talking particularly about testing 2 hour postprandial rather than immediately after eating, obviously) - my highest blood glucose reading is my fasting one. Unless I've had way more carbs than I should, my 2 hour postprandial test will be comfortably under 8mmol/L, whereas my overnight fasting is rarely under 9 due to the dawn phenomenon. My A1C is usually around 5.5-5.7.
  • chelny
    chelny Posts: 179 Member
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    Ok, point taken about dawn phenomenon. Still, the A1C is an average over a period of time. Testing blood glucose at 1 point in time is not necessarily going to "agree" with the average. She's given us some tests results that were only fasting. We don't know her post-meal test results to consider.

    I did find this online: If you have iron-deficiency anemia, your A1C test results may be wrongly high VS with other kinds of hemolytic anemia, A1C test results might be falsely reduced. (https://diabetesbros.com/hba1c-to-mmol-l/)
    Does that help?
  • lorib642
    lorib642 Posts: 1,942 Member
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    Yes it does help. Thank you
  • 2t9nty
    2t9nty Posts: 1,572 Member
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    My fasting number is sometimes my highest reading of the day, so if I only tracked fasting, it would be a poor prediction of A1C. This stuff seems to vary wildly by person.
  • lorib642
    lorib642 Posts: 1,942 Member
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    I know I took a reading before dinner and it was 118 which is not great, but it is closer to my A1C result

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