Dexcom Clarity

Capture - Dex Clar

Hi all Dexcom Clarity users. Wondering if someone can tell me if the 7.7 or the 6.6 is my estimated A1C? Either way I’d be thrilled, as my last few have been 8s/9s/10s. I’ve been trying really hard to keep my BG’s stable of late.


The GMI 6.6% is the estimated A1C.

It will be more accurate based on sufficient readings, eg 1-3 months.

6.6 is great!!


Thanks. This was based on 14 days, but even when I do 90 days, it’s below 8, which was my first goal. Then, under 7 is my next goal. So cool to see this progress!


You can also this calculator to estimate GMI/A1C.

Tracking progress can be very motivating!!


@jo_jo It’s great you’ve been able to lower your A1C as much as you have! The GMI (Glucose Management Indicator) is the same as a eA1C (e=estimated) derived from the CGM readings. They reflect the BG mean and can be based on a different number of days data; most recommend at least 14 days to be meaningful. The SD (Standard Deviation) is a measure of the spread of BG readings over time. Again, different apps can use a different number of days data to calculate; if used in conjunction with GMI, it should use the same number of days data. Most people recommend a SD less than 1/3 of the GMI; you’re right in there! The other function many use is CV/COV (Coefficient of Variation). It divides the SD by the BG Mean (i.e. the GMI) and multiplies by 100 to five a percentage; it provides a refined understanding of the SD. The higher the CV, the larger the swing of BGs.

Rather than do the calculations yourself, several apps will do them for you. I use Sugarmate connected to my Dexcom data; it allows me to change the number of days/hours for different calculations, makes for a no-cost nightstand display of my BGs without having to put my glasses on, and even calls my phone when I’m going low!

And now you’re saying: “MATH! No body told me there’d be MATH!”


Luckily, my Mother is a retired Mathematician! :nerd_face: Thank you for the thorough explanation!!



Congratulations on your progress. Those are excellent numbers!

As others have noted, looking at things like the standard deviation and time in range are increasingly popular numbers as compared to HbA1C.

If we assume that you average Dexcom readings stay at 7.7 mmol/L (about 139 mg/dL)
for 30 and 90 days, then your “predicted” A1C will indeed be 6.6. Will your next A1C measurement ACTUALLY BE 6.6? Probably not. Many of us find that there is a fairly consistent offset between the predicted GMI and a lab-measured A1C.

In my case, for example, if I have a predicted GMI (based on 30-90 days of average Dexcom data) of 6.6 like you have, I am almost guaranteed to get a lab-measured A1C of 7.2-7.3. That is, I see an actual A1C that is 0.6-0.7 HIGHER than predicted by my average Dexcom glucose reading. Other people see that their actual A1C will actually be LOWER than their predicted GMI based on their Dexcom data.

If you compare your 30 to 90 day predicted GMI to your lab-measured A1C over the next few A1C bolo draw measurements, I predict that you will also learn that you have a fairly consistent “offset” between your Clarity-predicted GMI and your lab-measured A1C.

All of that detail aside, one thing is true:

From where you have started, a Dexcom average glucose reading on 7.7 mmol/L is impressive progress. Brava!!! You are clearly using the numbers that you see on your Dexcom to improve your glucose control in a positive fashion. Your math-proficient mother notwithstanding, pat YOURSELF on the back for using your Dexcom data efficiently!

I wish you continued success with your Dexcom-aided management.



Interesting. I’ve long thought that wild swings between highs and lows even with a decent A1C would be bad, but my first Endo said that didn’t matter only the A1C # mattered.

Yes, I will be happy just to be under 8! My appointment isn’t until the new year, so I have time to possibly get below 7, but I’m not putting any pressure on that. Progress, not perfection, is my aim:)


I kind of disagree with your endo on that point. An A1C of 5.0 isn’t good if you spent 25% off that time in low and severe low territory. My goal has always been to “get in and get out” of anything NOT our designated acceptable range, ASAP. It’s not good to linger in highs or lows too long. Lows the obvious immediate threats and highs also immediate but more long term ramifications.


I disagree too, and he’s not my Endo anymore. He was my first Endo. He also said things like if I only need 1 unit, there’s no point, like don’t even bolus if it’s only a unit!!


Me too, I always like this graphic from diatribe.

Perhaps @jo_jo should show this to the endo, or perhaps not.