How to Find out If Your Dexcom CGM Is Inaccurate (And How to Fix It)

Is there anything more annoying than an inaccurate Dexcom CGM sensor?!?
Let me show you an easy way to quickly find out if your sensor is inaccurate and when you should calibrate your sensor to make it more accurate.
Dexcom Accuracy Table HERE ► www.dexcom.com/faqs/is-my-dex...
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[@doubleohhhhseven]

I am a non-diabetic user of the Dexcom G6 (using it to improve my metabolic health along with a Levels Health subscription), and I've watched several of your videos about CGMs, and just wanted to let you know that I'm very thankful for all the content you put out. Than you!

[@jimsnider3828]

I was just diagnosed with Type 2 diabetes on 04/07/2023. Your videos are extremely helpful and very informative. Especially for a novice trying to learn as much as possible about both the disease and the Dexcom G6. I can't thank you enough for all of your hard work and dedication.

[@DiabetesStrong]

I know everything can seem very overwhelming, especially in the beginning, so I’m really glad you find it helpful

[@jackiefinley-ramey1178]

Thanks for the information I felt like I was going crazy with this Dexcom lol it's been telling us that our daughter low when she's not low, thanks for making these videos they are a lifesaver more than you know, my daughter being recently within three weeks diagnosed with type 1 she's only had the Dexcom on for 24 hours almost so hopefully things will start getting better it's just so new to us thank you for all of your information it helps people like me that are lost lol

[@DiabetesStrong]

You're very welcome. I'm glad this is helpful. You'll get a hang of it. I do find that with time, as you learn more, managing diabetes does become a little easier

[@johnwilliams4100]

I found if I calibrate twice it works better. Most times it doesn't accept the calibration if it's only entered once. I then wait 20 minutes and Ive noticed it's much more accurate.It's that 15 minute lag time that's scary. Ive returned many sensors and transmitters. Dexcom always sent me new ones a timely manner. Thanks for all your helpful videos! God Bless

[@DiabetesStrong]

Yes! I agree, the double calibration is often the way to go

[@TheRALPHIE0211]

Thank you for spreading this info... HUGE warning to everyone, make sure to be especially sure to wash your hands after handling glucose tablets as these will drastically throw off meter fingerstick readings. Also, if you find yourself in a situation where you need to fingerstick and don't have access to a sink to wash your hands, sucking on the desired finger and then wiping it off on your clothing does the job. (in the car, walking thru the mall, in the woods, etc.)

[@DiabetesStrong]

Great addition, thank you

[@psdaengr911]

If you recently took glucose tablets, and chewed them to promote rapid digestion, sucking on your finger is the worst thing you could do. ( Hand sanitizer that is 30% water is better than no water at all.) I rarely need to to do it but the time to suck on a finger is before I handle glucose tablets, and the hand I sample is my off hand on the side of a central finger that's away from my thumb. The correction ruie is to "test then correct". If you're in a situation where you have to correct before you can test then you're in trouble. If you can't tell the difference between hyperglycemia and hypoglycemia from your symptom then you're in bigger trouble and a caregiver should be making your diabetes decisions..

[@brucepethick3999]

Hey thanks for your very informative video loved it!!!

[@DiabetesStrong]

You're welcome, and thank you

[@ALeaud]

Thanks for this. Your video is super reassuring for me. This is my 3rd day with my Dexcom G6. First day was about 2.0 mmol off. Second day was about 0.8 off. Now on the third day it’s around 0.8 again which is fine but for some reason tonight it’s been telling me my sugar is really low when it clearly isn’t. I’m gonna check with my Accu-Chek Mobile in a few hours and see how it measures up before I sleep.

[@DiabetesStrong]

2 mmo/L is too much for it to be off but I agree that 0.8 mmo/L is acceptable. Hopefully, it won't be too off when you measure, but if it is it might be worth doing a calibration

[@ALeaud]

@@DiabetesStrong I checked it and it was about 0.9mmo/L off so not so bad. I just assume when it's telling me it's 7.0 it means it's actually 6.0 which is fine. I'll definitely calibrate it if it's still off the next time I use my meter. Thanks again!

[@sameerdoultani7854]

Thank you for this video, very helpful. The sensor I have on my child was way off (as per the table on the dexcom site) compared to the meter. I calibrated it immediately; I am wondering how long would the sensor take to get back to accuracy.

[@DiabetesStrong]

If the sensor is completely off it might take you a few hours. Some do a "double" calibration, so 2 calibrations right after each other to force the readings into the proper range. If it's not within range in 3-6 hours I would request a new sensor. You can easily do that in the app, no need to call them)

[@sameerdoultani7854]

@@DiabetesStrong - Thank you for your prompt response, I really appreciate it!

[@wandacampbell9839]

Hi I am new to your videos but love them very helpful. Mu husband is using the dexcom for about 3 year little to no problem ever but now his readings are off 50 to 100 points every time we finger stick like 4 times a day. Should we calibrate? Hus test strips are expired but I tested my blood perfect 97 to 100 with each test so I feel they are accurate, please help I font trust dexcom anymore :(

[@DiabetesStrong]

If you're confident the test strips are accurate you should probably calibrate. Any chance you still have the control solution so you can test if they're accurate?

[@crystalzastrocky8347]

Have had my g6 for about 5 days no issues as of now I love it

[@DiabetesStrong]

Awesome

[@blugoose86]

Thank you for sending me this link. I have a little bit better understanding. Now for another question. When I recalibrated my sensor, it didn't actually calibrate to match my meter, so I recalibrated again. Does the first recalibrate just put the reading within the 20% of the sensor tolerance? Should I just recalibrate once?

[@DiabetesStrong]

Glad it was helpful. That’s a great question. I believe Dexcom recommends only calibrating once but I’ll sometimes do a double calibration if it doesn’t align fast enough

[@briannamottola]

I have an Omni pod and a dexcom g6.. I came here and I don’t feel so alone anymore after seeing all the comments of so many type ones💞 I got really lucky because most of the time my sugars are very accurate.. if I start to not feel good I usually notice that the meter correlates with how I’m feeling

[@DiabetesStrong]

That makes me so happy! Glad you found this channel and that your devices work well for you

[@Steve-yu6pq]

Thank you! I’m new to the G6 and I’m noticing I’m about 10-20 mg higher on my g6 then poking myself. It’s making a little worried but sounds like it still falls in the accurate range.

[@DiabetesStrong]

Yes, that is considered accurate. Glad it was helpful

[@martinm.438]

Yes that sounds about normal. I have a sensor is off by 50

[@bezafantu8933]

Hi dear my son use g6 but we have issue with. withen 2 hours after he ate he goes low.wheni gave him some food or drink he goes up. at this point after 2 hours he goes high over 200. and my question is I have to wait it complete 2 hours then tritment?

[@DiabetesStrong]

A few things to think about. - When my Dexcom reads a random low (such as sudden drops) I often confirm with a finger stick. - - Try the 15:15 rule, treat with only 15 grams of carbs, wait 15 min and see if he's back in range. - If you over treat (it happens!) with too many carbohydrates you might have to give him insulin to counter the extra carbs. I don't know if there's a rule for how long to wait until you treat but I'd think 2 hours is plenty

[@FlyinRyanProductions406]

I’m a month into use with mine. I have the best luck on the inside of my upper arm (not fda approved). My sensor has been within + - 10. I also don’t seem to put pressure on it there. 🤷🏻‍♂️ on my belly I was + -20 and laying on it would give be bad readings.

[@DiabetesStrong]

Awesome! I haven’t tried placing it there but it makes sense. Glad it’s working for you

[@patrickdzieniak9311]

So it’s better to calibrate right after putting it on ? And do you double calibrate or once ?

[@DiabetesStrong]

No need to calibrate it unless it’s very inaccurate. I try to limit calibration the first 24 hours and only calibrate if it’s way off. Double calibrations with Dexcom G6 make sense to me

[@wolfieziggy19]

My problem is that when I try to calibrate the cgm it does not hold the calibration; I have to keep inputting the correct numbers before it sometimes "keeps" the re-calibration. I've tried calling Dexcom on several occasions and I wind up even more frustrated because of communication problems. I sometimes wonder what's the point in using something that has built in inaccuracies; sometimes the spread between the finger stick numbers and the cgm are off the chart!

[@DiabetesStrong]

I know what you mean, sometimes the calibration won't stick. Aside from trying a few times in a row, I don't have any other ideas on how to try and fix it

[@Red1Wollip]

I am just going to start using the G6. I hope it works for me.

[@DiabetesStrong]

I hope so too! Good luck

[@BIGG-MATT]

I am brand new to the Dexcom G6 system. I am still on my very first sensor. I questioned the reading so I checked with my meter and it was off by 40 points so i thought I would try my backup meter and it was 83 points from the G6. I understand stand they wont be the same but my issue is "WHICH ONE IS THE CORRECT ONE? ". If the G6 is actually the one that is most accurate, then calibrating it to the meters will make it inaccurate. How do you onow which one is correct?

[@DiabetesStrong]

I trust my glucometer. If off I’ll do a few extra finger sticks to verify and calibrate the sensor

[@zxljmvvmmf3024]

I'm having a lot of issues on my left part of body with the G7. Had two bleeder which stung a lot. Soooo frustrating :(

[@DiabetesStrong]

That sucks! I have to ask, you have the G7?!? How do you like it?

[@mrpowers4667]

I feel like mine is very off. My “levels” have been above 400 and not moved for two days. Mind you, I’m skinny/athletic build, I’ve been eating healthy, I’ve been exercising, etc. And yet, the meter has not moved from “HIGH.” If I’ve had these levels consistently high for this amount of time, shouldn’t I be incredibly ill? I’ve felt totally fine this entire time, so this sensor has to be off?

[@DiabetesStrong]

If you suspect that the sensor is off you should do a finger stick to confirm. Running that high for extended periods would make most feel ill, but your tolerance might be different. Time for a finger stick...

[@brianfontenot8264]

I'm on the dexcom g6 and have so many problems with my sensors it is unreal. BAD BLEEDERS, SUPER INACCURATE READINGS, Sometimes it will show my BG all over when it is not I can't wait until the G7 is integrated with my tandem tslim x2 pump. I hope that is going to be much better than the G6

[@DiabetesStrong]

😕

[@sonalkaushal5614]

Anyone else having this problem? My son was not getting data for about close to 2 hours. I decided to poke his finger to see the reading. We completed the glucometer process and it read 423(which was shocking!) but at the same time, we got his reading on dexcom g6 and it read 79. This has happened a few times in the past and i’m just not sure if I should trust dexcom reading anymore. My son’s A1C comes much higher than what the dexcom indicates as well. Has anyone been through this or has any suggestions?

[@DiabetesStrong]

That's an enormous difference!! I understand why you're starting to have trust issues. I think I would start every day with a finger stick just to assess the accuracy. I would also test different placements, you might see better accuracy on his arm than the stomach for example. Might be worth a try...

[@sonalkaushal5614]

@@DiabetesStrong we have decided to poke his finger every night before going to bed. If the difference continues, we definitely will try his arm or something. He does wear his omnipod on his arm so it might be little tricky.

[@6468May]

How do you calibrate it? I guess I should watch this whole thing in case you go over it

[@DiabetesStrong]

I of course appreciate any watch time 🙂 But in the app click “settings” and then scroll down and click “calibrate” then you just add your blood sugars and save

[@alyssaheady2000]

Is it normal for the Dexcom G6 to be more than 100 mg/dl almost every time?

[@DiabetesStrong]

More than 100 mg/dl off from finger sticks? If that’s the case I would calibrate

[@moodberry]

Good advice. But a question...When I calibrate, I input a new number from my meter, and then hit save. The number I input doesn't show up on my Dexcom. But if I input it again and then save, the new number DOES show. So what's going on here? Why do I have to input the number twice in order for it to show? Thanks.

[@DiabetesStrong]

Thanks. You are right it will only adjust to the level you’re entering if you enter it twice. As I understand it, when you only enter one reading it adds it to the “calculation” rather than just course correct immediately. I’m not sure why

[@moodberry]

@@DiabetesStrong Wish I knew. I am not sure which method is best. Enter once, or enter twice?

[@DiabetesStrong]

@@moodberry if the sensor doesn’t adjust fast enough or is VERY off I’ll do two calibrations but I often find one is enough. I don’t know if there’s an official set of guidelines

[@psdaengr911]

Dexcom never says anywhere that their sensors can be wacky. They never state that there is a period of up to x hours of instability after the f2-hour warm up. They proudly advertise as the main selling point that the FDA has cleared the device making management decisions with no calibrations and no finger sticks, then bury in the fine print the implication that you can't rely on the sensor values. Imo, the value of the G6 is being able to see the direction and rate of change at a glance. That's true whether the G6 is used standalone, in conjunction with a pump, whether open or closed loop. Ive had a sensor go wacky four days after insertion, then fail in the middle of the night. Now I can't imagine not using a finger stick meter at least once a day when stable before bedtime. That's the only way that you can determine whether G6 is within 20% of meter tolerances. My experience has been that when my blood sugar is changing faster then the lowest sensitivity setting then I will get alarms long before I have any symptoms of hypoglycemia. (You don't experience symptoms of hyperglycemia unless it's prolonged and pronounced. ) The time to be most concerned about a G6 sensor is if it consistently reads high. Correcting for false high readings is less immediately dangerous thean correcting for low readings. False low alarms are a nuisance and only become dangerous if you turn off or muffle the receiver so that you do not hear the alarm, become conditioned to ignore them and / or the experience about paranoid about accuracy. You should only recalibrate when your BG is stable, but depending upon your personal objectives the best level at which to do that will vary. eg If you are trying to avoid nocturnal hypoglycemia but your average level is low, say between 80 and 110 the before-meal goal, it would make sense to do a (re)calibration when you are stable near 100. If you're constantly getting. false extreme low alarms then you would want to calibrate at a lower level but above 80 mg/dL

[@crackerass69691]

what's the point of the dexcom G6 if it's not accurate? my daughter's had it for about a year now and it's horrible. the other day it said she was 54 and she was actually 160. that's a huge difference that's dangerous so when you think you're that low and you start eating food to get your levels up not realizing you were at 160 now you're dangerously high. how is that a good thing? dexcom does not work it's horrible

[@DiabetesStrong]

That's not a good thing! Those are some awfully large inaccuracies you see with your daughter. I wouldn't be happy with that either. I haven't experienced that large differences but not sure I would stay with the system if I did. No technology is perfect but if it's constantly off I'd have a chat with Dexcom and see if they can help you pinpoint the issue

[@thecandyman9308]

Yes I'm flabbergasted that so many people fawn over the Dexcom + Tandem T Slim combo. It's been nothing but headache after headache for me and has made managing my diabetes way more difficult and stressful.

[@crackerass69691]

@@thecandyman9308 it's a nightmare. the app only works like 25% of the time. ugh. unreal

[@treal4lyfe935]

How do you calibrate?

[@DiabetesStrong]

In the app, click "Settings" and the "Calibrate" and enter the blood sugar

[@BeHai82]

Hi. Thanks for the video. 🙂 I restarted the dexcom g6 for the first time today (followed your other video). It worked but the numbers are total false compared to finger stick. Dexcom shows 220mg and finger stick 138mg. Shall I do a calibration?

[@DiabetesStrong]

I would probably calibrate. I had one that was very inaccurate as well. I did calibrate but ended up just taking it off as it never adjusted. But you probably need to give it at least 24 hours to adjust

[@Scott-ek7qj]

@@DiabetesStrong I’m actually glad I stumbled upon your video. I’m new to Dexcom. I use to use the Libre and made the switch for a couple of reasons. I went to take a nap as my sensor was in the warmup mode. When I got up my wife asked me if it worked. I responded if you mean that it didn’t let me sleep because it kept going off on high alerts. It went from the 250s, to the 260s, I even changed it to an alarm of 290 and that went off. This made no sense because my sugar doesn’t generally go that high. Well, I looked and it was 170+ and I stuff my finger and that was 120+. My wife asked if it was the same as the Libre where the first day is funky as it gets accustomed to your body. I responded that I hope not because these sensors are for 10 days vs 14, which means you are now losing 10% already. I’m glad to know that may very well be the problem after watching your video. But, you actually raised a different point that I never investigated. Everyone always looks at the sensor on whichever CGM you are using as its the cause of the faulty reading. However, it could be your meter’s fault. So how do you make sure that your meter that’s measuring your blood is accurate? I’m definitively going to wait the full 24 hours to see if the Dexcom is at minimum more in line with the scores I was receiving on my Libre first and foremost. If it turns out they are, well I would like to find out if my meter is accurate. Do you have any ideas how I do that? I know all the different CGM guides suggest to make sure they are accurate by comparing to your reading on your meter. But what if that is off…..I just don’t know how you find out. Ironically, you mentioned the expiration on the test strips. Everyone I know who uses test strips tell me that their expired strips will not work literally the day after they expire. Yet, the brand I’m using don’t ever seem to stop working. Because I’m using the CGM, I don’t use the strip as often (the point of the CGM). So I still have some strips that have expired in the beginning of 2020 and I’ve compared those to the ones that are still good as well as ones that expired at the beginning of this year and all of them give me the same reading. Could that mean that my meter is bad, could that mean that even my expired strips as still good, or could it be something else? How do you double check? Luckily, I’m not on a pump yet. But there has been talk of that potentially being a possibility if this new plan doesn’t work. That’s pretty scary If the technology is not working and that may result in the wrong amount of insulin delivered (unless the pump works differently than what I thought). I would appreciate your input, especially how to check your bg meter. Thanks in advance.

[@DiabetesStrong]

@@Scott-ek7qj I used to have a meter that had a “test” solution you could use to check if it was accurate. My current meter doesn’t. So how do I know if it’s accurate? I have two meters and if in doubt I’ll do a test on both. I accept them to be slightly different (+/- 10-20 mg/dL) but that’s it. And I agree that the inaccuracy is concerning when you use the readings for dosing or a hybrid closed loop pump. As of now the only real way to get around that is to check the readings up against finger sticks until you trust the CGM

[@Scott-ek7qj]

@@DiabetesStrong Thanks for the quick answer. Unfortunately my solution expired. I need to get more. I don't even know if it was a good meter because I was forced into using it. It was necessary because it was the same device I used to scan my sensor for the Freestyle libre 14 day. Do you suggest I get a different meter? If so which one do you suggest? Do you use that one, if you don't mind telling? Also, I still have left over libre sensors, can I use those to also help calibrate the G6? Or does it have to be the blood? And lastly, will it hurt if you calibrated the device even if it's within the error cone? I guess I'm now asking these questions because I noticed the same patterns since moving to the G6, but my scores seem to be higher. Unfortunately, because my last several orders took so long to come in, I ran out of my unexpired test strips. Because I was using the Libre, I didn't use the test strips that often, that I have several boxes of expired strips left. I wasn't aware I would need these strips with the G6, especially so soon. I will call tomorrow and see what my insurance covers now that I no longer need to use that specific meter since I am not using the Libre. They still may want me to use those same strips, but they may want me to use a different meter with different test strips. Hopefully, you wouldn't mind giving me your guidance and advice. This is way more confusing than one would think and should be. Thanks again in advance for your help.

[@DiabetesStrong]

@@Scott-ek7qj I have an Accu-Chek meter that my insurance covers, it's ok. I've also bought a Dario meter, that's not covered by insurance, but it's consistently accurate so I use that for calibrations. I'll link to my review of Dario below. I wouldn't use another CGM for calibration as it measures in the fluid and not the blood. But if it gives you peace of mind and you have them you could wear both for a while. Finally, Dexcom says to not calibrate if it's not considered "inaccurate", I'm not quite sure why...

[@Nobodymidd]

My 9 year old boy has a g6 but the big problem is it needs changing every 3 to 4 days fails all the time hope dexcom 7 is better

[@DiabetesStrong]

Oh no, that's annoying. Hopefully, Dexcom sends you replacements. I don't know why, but some people's bodies just don't seem to agree with specific sensor brands. Another brand might work better for him

[@chroniclesofsunshine4484]

It’s dangerous when dexcom says 6.5 and stable , and my meter reads 2.2. After 3 times of near collapse due to low blood sugar (unalerted by dexcom) I have ripped this sensor off and will never use again . I’ve since switched back to my freestyle libere With no near death experiences anymore.

[@DiabetesStrong]

Yikes, that is scary!

[@FuzzyJohn]

They say that "home blood glucose meters are considered clinically accurate if the result is within 20% of what a lab test would indicate". Then the Dexcom G6 CGM is considered accurate if the result is within 20% of a home glucose meter. I think that puts the G6 kind of low on the accuracy scale.

[@DiabetesStrong]

I get what you’re saying. Mine is usually not that off. A better measure of accuracy when it comes to CGMs is the MARD (mean absolute relative difference). Dexcom G6 MARD is 9% and for comparison Freestyle Libre 2 MARD is 9.3%, Eversense E3 is 8.5%. and Medtronic Guardian 3 MARD is 8.7%. The lower MARD the more accurate. So Dexcom is not the most accurate but not the least either

[@abram730]

Dexcom g6 continuing to drop, down to 46 mg/ml Blood reading steady around mg/ml 140 like always mid day to PM. Not even close. Just put it in today. Actually never goes under 130 even if I go a week without eating. Morning numbers are mid 200's unless I eat something sweet at night and don't take the insulin, then it's mid to high 100's. I was told to increase the slow acting insulin by 2 units a day until I got under 130 fasting, but it went up topping out in the high 300's, 374 before I ran out at a dose of 182 units at night. Next morning after I ran out, it was 197 and stayed high hundreds, low 200's until I got more of the slow acting that raises my blood sugars. Doctors, like flat earthers, don't listen though.

[@centaur2656]

I was at 6.9 and it’s saying 2.2 mmol

[@DiabetesStrong]

That's way off. I would redo the finger stick and if it's still that much off do a calibration

[@shannonkiehn9337]

Ive had this meter for 6 months or so. This meter is ALWAYS wrong!!!!!! Giving it back to OHSU dr's!!!! Im done!!!

[@thecandyman9308]

yeah it's been an extremely stressful and frustrating experience for me too. i hate it.

[@MyajTellItLikeItIs]

My 6yr olds dexcom keeps saying that she’s 68 but when I check her finger she’s reading at 359 she just got the dexcom this is our first time using it since we got it she’s been on it for 6 days so far and now it’s doing this

[@DiabetesStrong]

That's beyond frustrating! If it's way off for me, I always go through the routine of rewashing my hands and doing 1-2 more finger sticks to just make sure that the reading is right. I"ll then check the chart I show in the video to see if I should calibrate (with as large of a difference you probably don't have to check) and calibrate if needed. I don't think I've ever seen as large of a difference as you mention. It could mean that the sensor is faulty. If that's the case you can call Dexcom and they'll replace the sensor

[@SteelheadJEDi]

It me it sounds like a combination of dirty fingers and pressure on the dexcom sensor. If I sleep or lay with a lot of pressure on my sensor it gives a false low. Especially on a memory foam mattress. I relieve pressure and heat from dexcom sensor, wash my hands and prick my finger and usually jumps back being accurate.

[@lowbudge007]

Irritated because leaving my 7 year old (who is just 12 days into diagnosis) at a friend's house to play with her reader is nerve racking. It being 50 to 80 off really gives too much guessing. I have fought this thing for days.

[@DiabetesStrong]

😕 I’m sorry to hear it’s not working well. If it’s that off for days, I’d take it off and request a new sensor. It’s only helpful if it’s working

[@Hueffed]

My Dexcom has been 300 points different than my One touch.

[@DiabetesStrong]

Uh, that’s not good. Time for some serious calibration

[@martinm.438]

My dexcom 6 is like off by like 50 points

[@DiabetesStrong]

If your blood sugars are stable you could consider calibrating the sensor

[@smgames9873]

Mine keeps telling me my sugar is 300 but it’s actually around 190

[@DiabetesStrong]

That’s frustrating! I would calibrate and if that doesn’t fix it, contact Dexcom for a replacement

[@mistersmith7391]

Dexcom. Blows. You can't even keep logs, add notes, cheats or details. Only input is carbs grams... who the hell carrys a scale with them 24/7. And disable screenshot? Software is horrific.

[@johnsnow5393]

use xDRIP ;)

[@bonniedulong224]

Do NOT get this thing. Mine has never been right. I just want this expensive piece of crap gone