Doctors reading is lower than my meter. Should I worry?

Hey there! I’m looking for advice on whether or not this should concern me and if I need to replace my meter? Would try test strips first but still a little not sure if that’s the right action.

So I had a routine physical yesterday. Since I have my endo appointment in 3 weeks and my primary and endo are in the same clinic network I just got my diabetes labs done at the same time with my physical stuff. I got a notification from dex that I was 71. Since I had IOB I tested via finger stick and got 72. Okay great right in line. Popped a gluc tab, let the lab tech know I just did that and she drew the blood.

Anyway hours later I got a frantic call from a panicked nurse saying that my labs showed my sugars were at 52. I have a hard time believing this because usually once I hit 60 I’m symptomatic. I told her I knew I was low, I’m fine now and that I’m diabetic so while I appreciate the call, I was so worried something else popped up in my labs. Here’s where it gets interesting though. My labs showed my A1C at 5.3. While that’s a fantastic A1C, my actual dex shows the guestimation at 6.1. I definitely feel like my A1C is more in line with that, but curious if it’s possible for the clinic lab to read extremely low? I’m running on average jd say around 115-120 as a daily average, I’m still seeing some 200s here and there and the occasional low low. But for the most part I’m hoovering between the 80-130 range.

So what do I trust? Two meters that are close in line or the clinic labs? My dex is also usually within a few points without calibration to the meter I tested with yesterday too.

I’m not a medical professional so this is just my personal opinion, but since your Dexcom and meter are in line I wouldn’t worry about it. I don’t know if the sample “degrades” over time but since the call came a few hours after the fact, I wonder if that might be the case. Or maybe somehow they messed up the sample.
Congrats on your A1cs - either 5.3 or 6.1 is excellent. I’ve heard that there are different reference charts for A1cs but that is a pretty big difference. Can’t explain it myself but either way I say you should celebrate your hard work.

Yes thank you! Either way I’m super happy with the A1C, just more concerned theirs came back so different. I’m planning on asking my endo about it just to understand, but my biggest fear would just be that I’m running a lot lower than I think I am but then at the same time, even let’s say my meter is 20 points off or so, im clearly treating lows and coming up but it would just be good to know because obviously if I’m dipping below 70 more often than I think I am, I should probably look at some setting adjustments.

Hi Taylor,

The only thing I can think of is that since you were in the low 70’s and took a glucose tab (single?), but still had IOB, you were probably still dropping. That would explain why the lab read you at a lower BG than you had before you went in.
As for the difference in your A1C, the Dex gives an estimate, not an actual A1C. So, I wouldn’t worry too much about them being different.

Pam K.
T1D 58 years and counting!

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Yes thanks that’s good guidance too. My dex held steady the entire time after popping it, so I’m not sure if it just didn’t register it but either way I’m not sure what happened! Honestly the part that just scares me is now that I have a really solid a1c, I’m nervous I’m losing sensitivity to lows, which is why the dex is great, but I feel like if I was 52 I should’ve been super symptomatic and I didn’t feel really anything.

Your body changes every second. The only time I would worry is if you take your meter to the doctors office and you both test at the same time and they are different. Each meter comes with a bottle of test solution, or it should. Try that to make sure it’s not the meter itself.

@Tee25 , according to Dexcom, below 80mg/dL, CGM to lab comparison is ±20mg/dL, so
Finger Stick 72
Dexy CGM 71
Lab Glucose 52

These three numbers are within a ±20 mg/dL standard published by Dexcom here:


Taylor @Tee25, the BIG question, is how did you feel - did you feel and act “a 52”? The least trustworthy reading you reported is the fingerstick meter reading. For that reason, I hesitate to ever calibrate my G6 using a meter. And there are many factors [including alcohol on finger] that can affect readings.

Look at MARD ratings [Mean Absolute Relative Differential] that compare BGL/BG CGM and BG Meter readings with the most accurate methods - hundreds of pieces of data used. the G6 has a reading of just under 6, and the best of meters are all 8 or higher; the lower the difference is superior. Interesting to note that the G5 tested better than the G6.

Also, labs can make mistakes. In August I had appointments one week apart with a GP and with an Endo, they each ordered lab work so I elected to save my vein and had blood for all work done with a single puncture; a couple of the doctor desires overlapped. On one report, the HbA1c was 5.5% and on the other report was 5.7% - same blood. My plasma glucose reports had a difference of 3 mg/dl.

Your daily averages look really good, and I suspect that your 5.3% HbAic is close - or nearer 5.5.

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