# Study of A1C vs GMI **URL:** \ **Category:** D-News\ **Created:** [March 16, 2021, 2:15pm UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082 "2021-03-16T14:15:43Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![CatLady](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/catlady/32/36_2.png) [@CatLady](https://forum.fudiabetes.org/u/CatLady)\ **Post date:** [March 16, 2021, 2:15pm UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/1 "2021-03-16T14:15:43Z")
> **[Using the GMI to Estimate Your A1C: How Accurate Is It?](https://diatribe.org/using-gmi-estimate-your-a1c-how-accurate-it)** > > GMI provides an estimated A1C level based on continuous glucose monitoring data and can avoid some of the limitations of A1C tests. A recent study compared actual A1C levels with GMI to see how the two compared in the real world. ---
**Author:** ![Chris](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/chris/32/382_2.png) [@Chris](https://forum.fudiabetes.org/u/Chris)\ **Post date:** [March 16, 2021, 3:54pm UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/2 "2021-03-16T15:54:16Z")
Interesting, at least in this study that data wasn’t all that close. ---
**Author:** ![Eric](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/eric/32/9209_2.png) [@Eric](https://forum.fudiabetes.org/u/Eric)\ **Post date:** [March 16, 2021, 5:37pm UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/3 "2021-03-16T17:37:44Z")
> Your glucose management can also be measured by Time in Range (TIR), when glucose levels are between 70 to 180mg/dL), Time Below Range (glucose levels below 70mg/dL) and Time Above Range (glucose levels over 180mg/dL). Time below 70? Meh. 🤷‍♂️ Not something I stress about. I think 60 is much less damaging than 180. ---
**Author:** ![Boerenkool](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/boerenkool/32/6307_2.png) [@Boerenkool](https://forum.fudiabetes.org/u/Boerenkool)\ **Post date:** [March 16, 2021, 6:01pm UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/4 "2021-03-16T18:01:11Z")
Too bad I can’t access the original study. I’d like to know whether the GMI in general overestimates or underestimates the A1c. I think this is a very important limitation of the study: “A perfect comparison would require a GMI and A1C taken on the same day with 60-90 days of CGM data.” “The average period for a CGM report was 24.5 days (the range was 14-144 days)” ---
**Author:** ![Boerenkool](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/boerenkool/32/6307_2.png) [@Boerenkool](https://forum.fudiabetes.org/u/Boerenkool)\ **Post date:** [March 16, 2021, 6:22pm UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/5 "2021-03-16T18:22:01Z")
> [@Boerenkool](#): > > I think this is a very important limitation of the study: “A perfect comparison would require a GMI and A1C taken on the same day with 60-90 days of CGM data.” > “The average period for a CGM report was 24.5 days (the range was 14-144 days)” In addition, I must say that I don’t think this makes the study worthless. It’s good to have some scientific evidence that you can’t extrapolate from 3-4 weeks of BG data to 2-3 months. It wouldn’t come as a surprise to me if many clinicians regularly printed just 2 weeks of data and took that as indicative of the past few months. ---
**Author:** ![CatLady](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/catlady/32/36_2.png) [@CatLady](https://forum.fudiabetes.org/u/CatLady)\ **Post date:** [March 16, 2021, 6:23pm UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/6 "2021-03-16T18:23:05Z")
That the GMI and A1C differed substantially for a majority of participants was very interesting to me since I am usually “off” by 0.5% as well. ---
**Author:** ![Boerenkool](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/boerenkool/32/6307_2.png) [@Boerenkool](https://forum.fudiabetes.org/u/Boerenkool)\ **Post date:** [March 16, 2021, 6:39pm UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/7 "2021-03-16T18:39:45Z")
In my case there’s a curious difference between the Freestyle Libre desktop software and the [Libreview.com](http://Libreview.com) reports. Reports generated on the same day have different estimated A1cs and GMIs. The desktop software was closer to my last measured HbA1c. ---
**Author:** ![Randy](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/randy/32/5435_2.png) [@Randy](https://forum.fudiabetes.org/u/Randy)\ **Post date:** [March 16, 2021, 9:09pm UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/8 "2021-03-16T21:09:49Z")
My xDrip A1c estimates from Dexcom G6 readings track closely enough with a medical office A1c test that my Endo wants the 30 day reading when we have virtual visits. She already has the data from my Tandem pump. I don’t think exact percentages are very important, but whenever xDrip tells me I have had a good A1c and TIR day it’s a real boost. Gotta do better tomorrow! ---
**Author:** ![TomH](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/tomh/32/9063_2.png) [@TomH](https://forum.fudiabetes.org/u/TomH)\ **Post date:** [March 16, 2021, 9:17pm UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/9 "2021-03-16T21:17:24Z")
Not quite sure I’m “meh” at 70; anything below 65 and my hands are shake yet and my mind’s fuzzy. Also, I find once I break 70, I tend to drop more quickly, it’s like my body says “Hey! If we’re going down, let’s go down quick and in style!” On the good side, I’ve found if I make a “small correction,” maybe 1/2 a glutab at about 75-80 (w/moderate down arrow on CGM), then wait a few minutes to see an impact, I can head off dropping below 60. ---
**Author:** ![Chris](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/chris/32/382_2.png) [@Chris](https://forum.fudiabetes.org/u/Chris)\ **Post date:** [March 16, 2021, 11:44pm UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/10 "2021-03-16T23:44:03Z")
Over time your body can get used to lower blood sugars if you spend a considerable amount of time there. When my son was first diagnosed anything below 100 used to have him shaking like a leaf. However, there is data to suggest that once you are over 65 you should have a higher blood sugar average than before. ---
**Author:** ![jbowler](https://avatars.discourse-cdn.com/v4/letter/j/e274bd/32.png) [@jbowler](https://forum.fudiabetes.org/u/jbowler)\ **Post date:** [March 17, 2021, 12:24am UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/11 "2021-03-17T00:24:51Z")
> [@Chris](#): > > Over time your body can get used to lower blood sugars if you spend a considerable amount of time there. I managed to adjust myself to 50mg/dl when I was first up in Oregon; lost in translation, I was used to mM and managed to do the division wrong, then stuck with it. It probably helped that I was “high” quite a lot. ---
**Author:** ![jeffsurfsncocktails](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/jeffsurfsncocktails/32/8961_2.png) [@jeffsurfsncocktails](https://forum.fudiabetes.org/u/jeffsurfsncocktails)\ **Post date:** [March 17, 2021, 4:12am UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/12 "2021-03-17T04:12:38Z")
@Chris @Eric @TomH Being new to actually being in tune with my sugars all of your comments caught my attention and curiosity. Eric mentioned low at 70 was nothing and I thought ‘holy crap I fell off at 75 somedays’ then Eric chimed in amd I felt better. I then thought that I was scared to go under 90 at one point. The moral is I think my BG was so high for long(had a 14 A1C) that it tool.my body time to get back to normal. Also learned about TIR from this article. I have enjoyed Playing the TIR game with myself and now it will be an even better tool. Thank you all so much for your insights and encouragement. Much Love, Jeff ---
**Author:** ![jeffsurfsncocktails](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/jeffsurfsncocktails/32/8961_2.png) [@jeffsurfsncocktails](https://forum.fudiabetes.org/u/jeffsurfsncocktails)\ **Post date:** [March 17, 2021, 4:15am UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/13 "2021-03-17T04:15:26Z")
FYI per xdrip my 90 day numbers are A1C estimate 6.9 TIR 72% ---
**Author:** ![Chris](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/chris/32/382_2.png) [@Chris](https://forum.fudiabetes.org/u/Chris)\ **Post date:** [March 17, 2021, 4:45am UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/14 "2021-03-17T04:45:52Z")
Congrats on sub-7 numbers! That is a big deal! Always good to get better at the diabetes “game”. And yes, glad you are appreciating the insights and encouragement, that is why we exist. Honestly, we would be lost without this group. My son was diagnosed 5 and 1/2 years ago and we were lost puppies wandering around in the wilderness of cinnamon cures wondering how we were going to do this, and then we met a bunch of great people and created this little corner of the web to keep passing on what we were learning. Thanks so much for staying around and contributing. ---
**Author:** ![Eric](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/eric/32/9209_2.png) [@Eric](https://forum.fudiabetes.org/u/Eric)\ **Post date:** [March 17, 2021, 3:01pm UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/15 "2021-03-17T15:01:46Z")
> [@jeffsurfsncocktails](#): > > Eric mentioned low at 70 was nothing and I thought ‘holy crap I fell off at 75 somedays’ then Eric chimed in amd I felt better. I then thought that I was scared to go under 90 at one point. Another part of it is the slope of the change. I guess I should have been more specific and said a **flat** 70 is nothing. If I am dropping quickly, and happen to test when it is passing the 70 but on its way down, that is totally different. I can actually feel low at 100 if it’s dropping. I think the important thing with BG is “where’s it gonna be 15 minutes from now?” ---
**Author:** ![Sam](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/sam/32/10595_2.png) [@Sam](https://forum.fudiabetes.org/u/Sam)\ **Post date:** [March 17, 2021, 3:09pm UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/16 "2021-03-17T15:09:21Z")
> [@Eric](#): > > Time below 70? Meh. 🤷‍♂️ Not something I stress about. I think 60 is much less damaging than 180. I agree with the theory but the complicated thing for a lot of people who have professional licenses dependent on their physical health is that they are evaluating for “hypoglycemic episodes” and those are a big red flag whereas elevated blood sugar is not at all ---
**Author:** ![TomH](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/tomh/32/9063_2.png) [@TomH](https://forum.fudiabetes.org/u/TomH)\ **Post date:** [April 8, 2021, 6:30pm UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/17 "2021-04-08T18:30:57Z")
@Sam I think this is the perspective my current Endo is coming from. Her advice last December was to aim for 100-150. When I questioned this at a January appt (and after doing some research myself) and suggesting 90-140 goal (I questioned a few over 200’s in the afternoon/evening), she commented at my age (65+) its better to err on the higher side and not to worry about 200-220’s unless its frequent/continual. I still like to keep it down under 140, except an hour or two post meals. Still figuring what’s right and what’s feasible. Managed to get my A1c from 10+ last Nov, to 6.6 last month and other numbers (Cholesterol, etc.) were good too, so was pretty happy and hope to keep them down. ---
**Author:** ![Chris](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/chris/32/382_2.png) [@Chris](https://forum.fudiabetes.org/u/Chris)\ **Post date:** [April 8, 2021, 9:38pm UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/18 "2021-04-08T21:38:46Z")
Keeping your A1c in the 6’s is what is recommended, I believe, based on the literature is that correct @docslotnick ? It would be if you venture into the 5’s that things are potentially too low based on the work that has been studied for people over 65. ---
**Author:** ![TomH](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/tomh/32/9063_2.png) [@TomH](https://forum.fudiabetes.org/u/TomH)\ **Post date:** [April 8, 2021, 9:54pm UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/19 "2021-04-08T21:54:29Z")
@Chris I think your advice is sound, though my PCM says recent studies for folks 65+ indicates upwards of 7 or a little more is acceptable IF not incorporated with bouncing between highs and lows frequently, i.e get a reasonable range and stay there as much as possible…seems good advice for a lot things! ---
**Author:** ![bkh](https://avatars.discourse-cdn.com/v4/letter/b/da6949/32.png) [@bkh](https://forum.fudiabetes.org/u/bkh)\ **Post date:** [April 9, 2021, 2:27am UTC](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082/20 "2021-04-09T02:27:01Z")
It sounds like you’re doing it right. For myself I like an A1C in the high 5’s rather than the 6’s on the theory that it does reduce the likelihood of damage. [Next page](https://forum.fudiabetes.org/t/study-of-a1c-vs-gmi/11082.md?page=2)