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Can you estimate your HbA1c from finger prick readings?

Discussion in 'Ask A Question' started by Cocosilk, Sep 16, 2019.

  1. Cocosilk

    Cocosilk Gestational · Well-Known Member

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    I don't have the best brain for maths but I'm wondering if there is a way to get an idea of your average levels by knowing roughly what your daily patterns are from having measured at home.

    Does anyone know if it can be done from several finger prick readings, perhaps looking across different days and calculating as if it happened everyday with a similar pattern?

    For example, let's say a fasting of anywhere between 4.8 and 5.2, let's call it 5.0.

    One meal a day with before being 5.4;
    1h being 8.5;
    2 hour being 6.5,
    3 hour being 5.5
    and between meals being between 4.5 and 5.5, call it 5.0.

    Then the other two meals being
    before 5.5;
    1h 7.5;
    2h 6.0
    and
    before 4.8;
    1h 6.7;
    2h 5.5.

    And before bed being 5.5 - 6.5, call it 6.0.

    And just use those figures to make an average reading. Is anyone good at maths?

    P.S. I will get an actual HbA1c soon anyway but it would be interesting to try to predict it before I get the real thing done.
     
  2. bulkbiker

    bulkbiker Type 2 · Master

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    As there will still be periods of the day when you have no idea what your readings are (when you are sleeping for example) any estimate will likely be very inaccurate. If you are wearing a CGM constantly it may give you a more precise guesstimate but they are also open to flaws.. as indeed is the HbA1c test itself.
     
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  3. Brunneria

    Brunneria Other · Moderator
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    Totally agree with @bulkbiker.

    Yes, you can test frequently, calculate your average, and come to a guesstimate.

    Or you can wear a flash glucose monitor or continuous glucose monitor, and get the gadget to come to a guesstimate using an algorithm that is beyond my ken.

    Neither of these methods will be particularly accurate, since the HbA1c is not actually an average of glucose readings over the last 3 months, it is actually an indication of how much glucose has stuck to your red blood cells over a vague timeframe that roughly equates to the last 2-3 months (the life of the red blood cell), and is heavily weighted towards the last few weeks, and further obfuscated by the length that your personal red blood cells live (it varies), and by a number of other health issues that you may, or may not, have (e.g. anaemia).
     
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  4. Kim Possible

    Kim Possible Type 1 · Expert

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    There are some apps that will estimate a Hb1AC when you plug in your finger prick readings.
    However, as Hb1AC is an indication of your average BG at all times over 3 months and you have readings for a few minutes of each day, any estimation based on finger prick readings can only be a very very rough estimate.
     
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  5. Jim Lahey

    Jim Lahey I reversed my Type 2 · Well-Known Member

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    Yes you can estimate based on your own readings, but;

    1. You'd have to test a hell of a lot in order to get an accurate picture of your average glucose.
    2. HbA1c is often an imperfect measure of average glucose.
     
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  6. Saur

    Saur · Well-Known Member

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    A lot of people have brought their HB1AC down on the forum. Any examples of how their readings has gone down and what their readings are now. What changes they made and how. My six monthly check has risen from 44 to 45. Very disappointed with the results but have to admit did have a lot of cheating days.
     
  7. xfieldok

    xfieldok Type 2 · Well-Known Member

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    MySugr app is free. When I first started, I was testing 6 times a day. After 6 days it gave me an estimated number. The number a couple of months later was 37, the lab test HbA1c was 35, close enough for me. I found it highly motivating when I first started. You can record quite a bit of stuff on it, but most important is your readings and food.
     
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  8. Prem51

    Prem51 Type 2 · Expert

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    I thought my daily finger prick readings would give me a rough idea of what my HbA1c would be, when I started out.
    But it doesn't. My last HbA1c in August was 48 IFCC, my 90 day average on the day I was tested was 6.8, which would be 40.8.
     
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  9. Brunneria

    Brunneria Other · Moderator
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    Yes, I am the same.
    My HbA1c is usually around 5mmol/mol higher than my calculations predict (using a Libre and compensating for the fact that my Libre always reads at least 1mmol/l lower than my prick tests, using the Tee2)

    Other factors in play are the fact that HbA1c results are subject to some inaccuracy and different labs can produce different results.
     
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  10. Robbity

    Robbity Type 2 · Expert

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    For what it's worth I can usually get a reasonable "guesstimate" from my 3 monthly averages on my meter using our diabetes.co.uk converter. And from experience I know that this figure is always slightly lower than my actual HbA1c test results.

    Using Libre sensor software calculations my predicted HbA1c figures were way below actual results.- misleadingly putting me well into normal figures.

    However all these are simply general guides and not an exact science, and my pre and post meal figures are the ones I prefer to take most note of as these give some inducation of how what I'm eating affects my glucose levels. Though again other factors come intro play - medication. pain, stress, etc will also have an effect on levels.

    But after nearly 6 years I probably know equally well how I'm likely to be doing without guestimates from gadgets, and initially in the first coiuple fo months from diafnosis my levels came down to pre-diabetic without the use of a meter, simply by eating a reduced carbohydrate diet - but my meter has since been and continues to be a useful tool.

    Robbity

    ETA Duff link to converter fixed now!
     
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    #10 Robbity, Sep 16, 2019 at 11:29 AM
    Last edited: Sep 16, 2019
  11. Bluetit1802

    Bluetit1802 Type 2 (in remission!) · Guru

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    I have learnt to more or less ignore my HbA1c. Instead I rely on my finger pricking and my part-time Libre use (after compensating for it mostly reading lower than my finger pricks). The HbA1c keeps my nurse happy, but it doesn't make me happy.
     
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  12. Scott-C

    Scott-C Type 1 · Well-Known Member

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    I "test" 288 times a day with a reasonably well calibrated cgm, and it estimated 90 day hba1c as 34. The hospital reading was 31.
     
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  13. Rachox

    Rachox Type 2 (in remission!) · Moderator
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    Like @xfieldok I input my data into MySugr. The estimated HbA1c is always lower than my lab tests, however I just use it as a guide to see trends up or down.
     
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  14. Saur

    Saur · Well-Known Member

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    Can I ask what is a Libre and also cgm. I have seen these in the posts but have no knowledge.
     
  15. bulkbiker

    bulkbiker Type 2 · Master

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  16. MeiChanski

    MeiChanski Type 1 · Well-Known Member

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    Libre is a flash glucose monitoring system (FGM), it shows what’s been happening inbetween tests and overnight but you have to scan it to get a result. Whereas a CGM (continuous glucose monitor) produces a reading every 5 minutes to give overnight patterns and inbetween finger pricks.
     
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  17. Saur

    Saur · Well-Known Member

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    Thankyou both.
     
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  18. Cocosilk

    Cocosilk Gestational · Well-Known Member

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    I've measured overnight a few times since I am often up (was up a lot peeing while pregnant) and now up with baby.

    What I have never known is what level I should aim for before bed and what level is better to have overnight (not taking insulin but I am breastfeeding a couple of times through the night).

    The times I have measured I am usually in the 5s somewhere - sometimes mid 5s if I was high 5s or 6s after a late dinner. By morning, after 8 hours of fasting, I can sometimes be back in the high 4s but will creep up into the low 5s if I don't eat breakfast until 11am or so.
    Other times I am in the low 5s when I wake and it drops back into the high 4s if I don't eat breakfast until 11am.

    Maybe they are all just imagined because my metre could give half a mmol either way for no apparent reason and most of the fluctuations in my morning fasting levels are all within half a mmol usually. So maybe they are all the same difference. That's why I would call it around 5.0 mmol.

    My fasting before a glucose tolerance test was 5.1 while I was pregnant (and I ate a lot and late the night before because I didn't want to feel hungry... imagine! ha ha).

    My follow up fasting at 2 months postpartum was 4.4 mmol, but that was after probably 14 hours of fasting and I'd been breastfeeding during that time.

    In reality, I'm probably somewhere in the middle if I don't over eat or have to breastfeed.


    If I had to guess my HbA1c, I'm thinking somewhere around 5.5%. Could be more or maybe it's not quite there yet, if I am lucky. That means an average of 6.2 mmol I think.

    I think I see 4s more often than 8s, and I think I see 5s more often than 6s, and 6s more often than 7s. The 8s are because I'm playing around with some carbs again. Obviously sensitive to them. In the past 6 months I did see 3 or 4 times a 9.0 and a 10 mmol but I know how to avoid that now usually. I've likewise see 3.4 and 3.6 just a couple of times as well.
     
  19. Cocosilk

    Cocosilk Gestational · Well-Known Member

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    The link for the converter doesn't seem to work. It said "page not found".

    Wait, I found this one. Is this it? https://www.diabetes.co.uk/hba1c-to-blood-sugar-level-converter.html
     
  20. Cocosilk

    Cocosilk Gestational · Well-Known Member

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    I just calculated an average for these figures, just 10 of them, and got 6.14. That converts to a HbA1c of around 5.5%, which is what I guessed I might be just going on the feeling. So maybe the real one will come back even higher than that if that's what most of you found. Maybe I will be in the prediabetic range. Or on the dysfunctional end of "normal" but not yet diagnosable.
     
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