Dexcom CGM

I use the Medtronic 640g insulin pump and trialled their CGM sensors for a period of about 6 months and to my amazement the CGM had many problems. The main issue was that despite calibrating it as instructed it would only show correct glucose readings 20% of the time. It was a horrendous product and I strongly suspect you will experience the same issue with the Dexcom since this is another product that requires calibration.

If you are looking for accuracy and smartphone compatibility you should consider the Freestyle Libre. It is not a CGM but its a flash glucose sensor requiring no calibration that you can scan with a device called a Reader as frequently as you like.

CGM's do not work and I'm surprised they are on the market.

mark4785 said:

I use the Medtronic 640g insulin pump and trialled their CGM sensors for a period of about 6 months and to my amazement the CGM had many problems. The main issue was that despite calibrating it as instructed it would only show correct glucose readings 20% of the time. It was a horrendous product and I strongly suspect you will experience the same issue with the Dexcom since this is another product that requires calibration.

If you are looking for accuracy and smartphone compatibility you should consider the Freestyle Libre. It is not a CGM but its a flash glucose sensor requiring no calibration that you can scan with a device called a Reader as frequently as you like.

CGM's do not work and I'm surprised they are on the market.

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A bit confused why you are suggesting the Dexcom CGM will automatically not be accurate. Have you ever tried it? I find it extremely accurate, but the point of CGM/Flash GM is not so much to get a precise reading at a given time, but to see where your BG has been, and understand where it is heading. Whilst I personally trust my readings each and every day, what I would say is that when I see a reading of, for example 5.2, that in itself is quite meaningless, it is only when you add in the context of what the reading has been doing over the previous 30 minutes, how much IOB and how many carbs have recently been consumed, that you actually see the meaning of the reading.
As for phones, you should look at the Dexcom G5 for out of the box compatibility, as whilst you can do it with the G4, you would need to invest in some additional tech, such as nightscout and xDrip.
For anyone in doubt about the benefits of CGM, the book "Sugar Surfing" is well worth a read.

mark4785 said:

I use the Medtronic 640g insulin pump and trialled their CGM sensors for a period of about 6 months and to my amazement the CGM had many problems. The main issue was that despite calibrating it as instructed it would only show correct glucose readings 20% of the time. It was a horrendous product and I strongly suspect you will experience the same issue with the Dexcom since this is another product that requires calibration.

If you are looking for accuracy and smartphone compatibility you should consider the Freestyle Libre. It is not a CGM but its a flash glucose sensor requiring no calibration that you can scan with a device called a Reader as frequently as you like.

CGM's do not work and I'm surprised they are on the market.

Click to expand...

Interesting observation.
I have trialled both the Libre and the Dexcom G4 and my experience was the complete opposite of yours.
I wonder if there is something about our bodies/our activities/our diabetes which causes the difference.

Maybe it is psychological but I was more confident with the Dexcom reading because it was calibrated by me in my body rather than the Libre which is generically calibrated in the factory.

I guess the lesson is that it is horses for courses - the Libre suits some and a CGM suits others.
Therefore, if considering either, I would strongly recommend pushing for a trial (I had no trouble organising free trials for both) before investing any money.

paulliljeros said:

A bit confused why you are suggesting the Dexcom CGM will automatically not be accurate. Have you ever tried it? I find it extremely accurate, but the point of CGM/Flash GM is not so much to get a precise reading at a given time, but to see where your BG has been, and understand where it is heading. Whilst I personally trust my readings each and every day, what I would say is that when I see a reading of, for example 5.2, that in itself is quite meaningless, it is only when you add in the context of what the reading has been doing over the previous 30 minutes, how much IOB and how many carbs have recently been consumed, that you actually see the meaning of the reading.
As for phones, you should look at the Dexcom G5 for out of the box compatibility, as whilst you can do it with the G4, you would need to invest in some additional tech, such as nightscout and xDrip.
For anyone in doubt about the benefits of CGM, the book "Sugar Surfing" is well worth a read.

Click to expand...

The Dexcom CGM requires multiple blood glucose calibration input like the Medtronic CGM so I see no reason why the Dexcom would be anymore accurate, for me at least. When I say the Medtronic CGM was inaccurate I mean it would indicate a downward trend to silly readings like 3.0 m/mol when multiple physical lancet blood tests showed an upward trend on the other end of the scale. So it was providing inaccurate readings and trends.

Having switched to the Libre system, it is able to demonstrate accuracy in the readings and trends it provides at all times.

I got funded medtronic guardian cgm abd its so accuatevto within 0.1 or 0.2?the vast majority of times. I do not calibrate unless my bloods are static though, so this may be a difference.

They are only able to provide to those that are funded, like you said though. In the interim I would have gone with a libre and waited.

There will be a lag between the BG level of a finger pick and what a CGM measures, so I can see how only calibrating at times of static BG readings can help.

mark4785 said:

The Dexcom CGM requires multiple blood glucose calibration input like the Medtronic CGM so I see no reason why the Dexcom would be anymore accurate, for me at least. When I say the Medtronic CGM was inaccurate I mean it would indicate a downward trend to silly readings like 3.0 m/mol when multiple physical lancet blood tests showed an upward trend on the other end of the scale. So it was providing inaccurate readings and trends.

Having switched to the Libre system, it is able to demonstrate accuracy in the readings and trends it provides at all times.

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I find it funny that you're negatively reviewing a product that you've never tried...

Anyway, the calibration feature is actually a benefit, and the Libre's lack of one, is the main reason I migrated to a true CGM. Dexcom G5 in my case.

Your disproval of all CGM's because of your poor experience with one brand, is a lot like me never buying a red car again because the red one I used to own often broke down...

For your information, the Libre is not accurate at all times. That much is fact.

It's a shame you had such a poor experience with the Medtronic CGM, but I'm not surprised. It shouldn't put you off ever trying a Dexcom system though. Believe me, I wouldn't be investing money in garbage. Neither would thousands of other diabetics.

Please note with CGMs and Libres you are not advised to calibrate when you have arrows going up or down....

A libre needs 24hrs to settle... easily done after the first one is in.

The medtronic cgm is accurate if you dont calibrate whilst you have up n down arrows. Especially if you have had food/correction etc...

I have huge DP and do not intentionally calibrate when I know I can get rapid changes. Fortunately these are getting fewer, and if need be I do calibrate but normally I would never calibrate with any arrows in any direction.

CGM's are good nowadays. Years ago I had a freestyle navigator-and boy, that was useless and totally inaccurate. If someone can ouck holes in anything, its me!!

All CGM's and Libre for blood start up and any callibrations need levels without swings.

GeminiJohn said:

Thanks for the replies everyone I'm going to trial the Dexcom G5 as soon as I can....although the accuracy could be a little bit better do people find that the trend arrows are normally true!?

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Yes, absolutely ... [for me] the trend arrows are spot on. Don't invest assuming it is a replacement for finger pricks, but it definitely reduces the number required, without a doubt. It also gives your Diabetes team information about your control that you cannot imagine. You are able to give them 1440 BG per day, every day, but that value comes in the trends, more than anything. What I would say, is that for me, taking the average BG over a 3 month period, has always given an accurate (within 0.2 or 0.3) prediction of my HbA1c.

I have used both Medtronic and dexcom CGMs, but never tried the libre. Personally, I hugely prefer the dexcom: it's easy to insert, it didn't require 24hr warm up (for me), I never experienced a single sensor failure, I only very occasionally saw noticeable accuracy problems and these were usually attributable to an old sensor or fast blood sugar changes, it only needs calibration twice a day. In contrast Medtronic needs the sensor to be in for 24 hrs before transmitter is connected, medtronic wants calibrating multiple times a day yet will only accept a calibration if within 2 of what it thinks you are, I had numerous sensor failures (I have lost count), and had numerous occasions when accuracy was way out.

So, I don't get on with Medtronic, I find them high maintenance and unreliable. But I think maybe it might just be that my body is not a very good environment for a Medtronic sensor - I can't think of another reason why I get the rate of sensor failures I do.

On the other hand, I love the Dexcom. I find it easy to use and I'm confident in its accuracy. I'm desperate to go back to it!

So I think the experience between CGMs can be very very individual and variable, it's probably not sensible to write off all CGMs because of experience with one @mark4785

GrantGam said:

I find it funny that you're negatively reviewing a product that you've never tried...

Anyway, the calibration feature is actually a benefit, and the Libre's lack of one, is the main reason I migrated to a true CGM. Dexcom G5 in my case.

Your disproval of all CGM's because of your poor experience with one brand, is a lot like me never buying a red car again because the red one I used to own often broke down...

For your information, the Libre is not accurate at all times. That much is fact.

It's a shame you had such a poor experience with the Medtronic CGM, but I'm not surprised. It shouldn't put you off ever trying a Dexcom system though. Believe me, I wouldn't be investing money in garbage. Neither would thousands of other diabetics.

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Hi I’m currently on a Accuchek pump which is funded by hospital would you have to fund the Dexcom yourself? Have recently heard good things about this pump!!

This is a very old post.
Most people do have to self fund Dexcoms.