Dexcom accuracy

I’ve been Dex’ing =for over 8 years, starting with the Seen+. I love the system, I pay attention to my trends and they help me make wise decisions regarding dosing. I was doing 10-15 fingersticks a day before Dexcom, and continued. I kinda bought into the the HCP spiel that meters are the gospel. Wrong! In my case I have chronic anemia - have been =been anemic since birth basically. Anyway, the meter that my health plan covers has been shown (check out Diabetes Technology Society) to read higher than actual for people with anemia issues. The result was that by “confirming” a Dexcom reading with my meter I was treating (correcting) high bg’s I wasn’t experiencing and not paying attention to pending lows or actual lows (my meter would say I was fine). Ending up staring at EMT’s due to massive hypos. I managed to get invited to a seminar for local Endo’s on the accuracy of meters and learned about the various ratings (and their sources) and decided to pay out of pocket for the meter with the highest accuracy rate (although I don;t think the FDA acceptable margin for error of 25% is all that great - and there is no requirement that meters get periodic performance reviews). Now I only fingerstick to calibrate and I make my decisions based on Dexcom. It has been several months and I haven’t had a hypo where I needed help (even getting the husband to bring me a juice) at all.

I do look at the Dexcom about every hour or so, and tweak things (either change the basal, grab a few grams of carb, whatever) so I can flatline as much as poossible

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So, which meter are you now using?

Contour Next. I am now trying to somehow get my input into the process for the health plan RFP for meters etc. I can’t be the only patient with anemia issues, and to have a meter that reads too high could end up costing me my health (i.e. life) and their bottom line should I ever agree to go to the Emergency Dept.

To me, there isn’t really any major cost difference between the various known eter brands. It is the Pharmacy Benefit Mgrs (PBS) and health plan negotiation process that really impacts the rice - and that includes everyone whether they have coverage or not.

You don’t want to get me started that whole issue… But I will if asked

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Mine can read 20-40 points lower than finger pricks when I am below 80, especially on first day of new sensor. Also need to watch out for pressure lows. When by accident I sleep on the transmitter with the transmitter fully buried in the mattress, it will read under by 40 points or so and give alarm. I just turn around in bed and voila, just gained my 40 points back in 5 minutes. Too close to belly button and when spoon partner signal gets lost if transmitter is more than 1 1/2 feet away (leave receiver in pajama pocket and no problem). Other than that the trends are quite accurate and I only calibrate twice a day at 8 AM and 8 PM regardless of how far off it gets. I did try more frequent syncs when finger-stick out by more than 20/20 but just found myself chasing the algorithm which became a moving target.

I agree with you @artwoman! Anemia was my first autoimmune diagnosis (followed a few years later by Hypothyroidism, then T1…many years later). One of the reasons I depend so much on my Dexcom.

I’ve tried it all and I still get readings more than 100 points off and lots of other crazy stuff at times. It could be many things affecting it like my body reacting to the proteins in the sensor etc. Also even a reading that is 20 points off can make a huge difference for me. It would never be safe for insulin dosing. I know I’m not the only one so it really should not have been approved. Dex is great as I think I said and I need it 24 hours a day but I don’t rely on it to dose unless I have 1- 2 correlating sticks which are close and which match my symptoms.

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I’ve used tons of meters and I like the Contour Next meters the best. I have 3 different models and they all provide similar , accurate results, no matter how high or low I am. Other meters failed me at some part of the bg range.

I disagree vehemently with “it never should have been approved”. It works well for the majority, period. Maybe YOU have trouble, and so do others, but some people just can’t get certain things to work well for them, but that doesn’t mean the rest of the world should be denied a product, especially one as good as the Dexcom. Now I’m done arguing this pointless argument. Let’s both move on, shall we?

Please stop using caps. It’s rude In this context. We’ll have to agree to disagree :joy_cat: you’re entitled to your feelings but there’s no need to get carried away with it.

Hallelujah! (did I spell it correctly?) Please don’t start arguments about caps, nor call me rude for doing so. Rude would be for me to demean you.

By the way the way no mention was made of people being denied a product except by you. You might want to try to work on accuracy in your replies to what has actually been said.

You want to deny people the use of it by wanting it to not have been approved.

No. I never said that and I think you’re well aware of this. Your behavior at this point is trolling -this will be my last reply to you. Bye :blush:

meee, just so long as you know that I have key board issues, frequently switching to caps and not noticing until I have written a long post. I usually apologize for the error and admit that I am too lazy to do things all over again.

I have been using the G5 for several months now, and I am having much success, but I do test with my meter prior to every meal and snack.
I belong to a Dexcom group on Facebook, and I want to post a list of hints that one of the members gave there. I have found this to be very helpful.

  • You do not have to calibrate every 12 hours. Overcalibration=inaccuracy

  • Do it when it is convenient and only only when it is reading flat - as close to three of the same number in a row as possible.

  • Do the start up during a period of no insulin and no food if you can.

  • If it’s right… leave it be! If you only calibrate once a day, or even every 36 hours… it’s fine! Sometimes less is more!

  • That first calibration is key.

  • If the numbers are WAY off, do three calibrations, one every 15 minutes - again at a flat time - and that should get it back on track.

  • NEVER calibrate on a compression low! It will mess up future numbers. Just wake, drink water and roll over and wait. Dex will catch up

  • Hydration is key. Dex reads interstitial fluid. When dehydrated there is less fluid to read and it isn’t moving and reflecting the glucose accurately. Stay hydrated!!
    Good luck!

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I was using OneTouch with a Dexcom G5 for a while (both One Touch Ultra and Verio, the only strips covered by my insurance) and did have trouble with Dex accuracy. My average BG as implied by an A1c test was typically higher by about 10-15% than the average BG measured on the Dex G5, causing me to question all the Dex readings.

I eventually figured out that I can buy Contour Next test strips on Amazon for less money than my insurance copay for OneTouch strips. When I switched to Contour Next I became more satisfied with the Dexcom accuracy. I don’t have any hard numbers, not being a stats guy, but am convinced that (for me) the OneTouch strips were reading consistently low by around 10% compared to my “assumed actual” BG as measured on the Contour Next, and using those test strips was throwing off the Dex calibration. I’d recommend fine tuning your Dex calibration processes by trying a different meter/strips setup for those calibrations, starting with a new sensor session.

To make a long story short, my opinion is the Dex is a very useful tool for tracking trends and is especially useful for catching impending highs or lows before they occur. It has it’s limitations but with careful calibrations these limitations can be discovered and worked around.

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I get my blood drawn by a lab every 90 days. I make sure that blood glucose is one of the tests ordered. Immediately after the blood is drawn I do three fingersticks and record the readings. I compare the average of those three numbers with the lab value. I prefer the fingerstick average to be within 10%. Using this method insures that my fingerstick meter, the one that calibrates my CGM, is relatively accurate.

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Richard has some excellent information on dexcom. I was calibrating when it told me, and not paying attention to how the arrows were reacting . I am doing much better with my accuracy since only calibrating first thing in the morning and at bed when my glucose is more stable.

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I’ve been using the Dexcom G5 for almost a year now. I don’t know how I lived without it. I use my Phone instead of the Transmitter and love it. The only thing I have problems with is i lose signal but it comes back. My accuracy is sometimes off then the fingerstick. I calibrate sometimes twice a day. I use the freestyle test strips. I really like it and love that i don’t have to stick my finger alot. i test before i leave for work or go home from work and at lunchtime.

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I’ve found this to be very true for the G4 as well. In the beginning, I religiously calibrated twice a day. But for months it read 1 to 2 mmoL or more higher or lower and was rarely close to matching my fingerstick. Now, as soon as it gets pretty close in a new sensor session, I leave it alone, calibrating when readings start to stray. I get much more accurate readings.

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