Would implantable CGMs be more accurate?

On the implantable CGMs…
The problem I have with CGM accuracy is - I suppose from what they tell me - my body tissue is not very conducive to using the sensors.

They (the Dexcom support peeps) always ask me if I am lean. Since they always ask that question, and it’s not because they are trying to hook up with me on Tinder, I guess it is a known issue for Dexcom users.

Would an implanted one make a difference? Do they put it in deeper so it gets to body tissue that is more conducive to CGM use? Or do you think I would have the same problem with an implanted one?


Are you suuuuuuuure, they’re not trying to hook up with you? :smiley:

I found an article on the accuracy of the Senseonics Implantable CGM. According to the article (pg.2), “Currently, no long-term data on implanted sensor accuracy or longevity are available.”

Accuracy and Longevity of an Implantable Continuous Glucose Sensor in the PRECISE Study: A 180-Day, Prospective, Multicenter, Pivotal Trial


Depends on where implanted I would think. I believe the Sensesonics sensor is still in the interstitial fluid.

They might be looking on tinder or grinder


Eric, every system I have reviewed outside of one short lived venture into a vena-cava glucose sensor, sits in the interstitial space, and would have the same issues you describe i.e. problems in transmission of glucose via interstitial fluid.

With that said, and seeing how “adventurous” you are, you could probably convince a Doctor to implant a couple in places that are likely to have less interstitial transport issues.

On the same timeline however, phones are getting enough processing horsepower that the through the skin approach might become viable before you get old enough to get fat.


Bingo! That’s the one that @Eric wants!

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Are you talking about this one? Unfortunately I think it will still be interstitial. I haven’t seen any details that say for sure, but this kind of seems to say it is the same type of thing the Dex measures:

Dexcom, the current leader in CGM, has a sensor that works with an app for the iPhone and the Apple Watch. According to CNBC’s report, it sounds like whatever Apple’s working on would only differ by using light or an electrical current instead of a needle under the skin.

Didn’t Kristen Stewart wear one like that in the movie panic room back in 2000 ? I always thought they were a failure because there isn’t enough fluid on your wrist

I forgot about that Movie (Panic Room). I do remember the child having diabetes was integral to the storyline.
Just looked it up.

GlucoWatch G2 Biographer, manufactured by Cygnus
Sensors last for 12 hrs before being replaced
First approved by FDA in March, 2001 for Adults, 18+ years of age.
Supplement FDA approval in August 2002 to expand to ages 7 ~ 17.
Provides readings every 20 minutes
Integrate alarm features
3-hr warm up
Fingerstick calibration

A quote from Mike Walsh shows that Animas Corporation apparently acquired this and then killed it off effective July 2007 although provided one year of additional support to existing customers until July 2008.

“After calibration, the GlucoWatch then sent a low-level electrical current through a users’ body which pulled fluid through the skin. Electrodes in the device then monitored blood sugar levels. Some patients found this process very uncomfortable, even painful. Many reported skin irritation.”

The GlucoWatch® G2 Biographer (the Biographer) is a device that provides frequent, automatic, non-invasive glucose measurements. The glucose sample is obtained directly through intact skin. The device is worn like a wristwatch, and is used with a single-use disposable component, the AutoSensor, which attaches to the back of the Biographer and contacts the skin. Each AutoSensor provides the user with up to six glucose measurements per hour over a 13- hour measurement period, giving up to 78 readings per wear. The frequent readings provide the user with trends and patterns in their glucose profiles.
For each wear period, the user attaches a new AutoSensor to the Biographer and applies the device to the forearm or wrist. An adhesive on the AutoSensor and a watchband keep the device in place. After a 2- hour warm-up period, the device is calibrated with the result from a traditional blood glucose monitor. After calibration, the device automatically measures glucose for up to 13 hours. The user can display the most recent readings on the Biographer and can scroll back through previous readings to get information on glucose patterns.


As most movies they got it back to front as well - the actor is going into hypo quickly and gets the sweats and shakes but they are desperate to get some insulin to inject them with - which would kill them. Problem is hyperglycaemia and DKA is not something you can write into a movie script as it takes too long !
The phones will need to be amped up a lot as well - my dexcom G5 doesn’t even get through the bedclothes to my phone at the moment - I have to sleep with it under the covers with me !

That is funny. (Not the symptoms but the movie getting it backwards.) Obviously I haven’t watched it for a long time.

I find the transmission on the G5 to be inconsistent in how far it will function.

If have seen it fail to transmit as you describe when super close.
Other times, we have it going into the next room (through a wall) in our house with no gaps in cgm readings.
As well, I am consistently able to pick up the G5 signal in a (very) crowded gym from 50~75 feet away (going to both the Dex Receiver and the Dex Mobile app on the iPhone). I expect in the gym there are probably dozens of other Blue Tooth signals coming from other devices as well as I can see a bunch of wifi signals.

BTW - The best place we have found for the iPhone at night is on the bed next to the pillow on the same side of the body as the G5 transmitter is. I doubt it all has to be that exact but this does seem to work pretty reliably for us. I keep the Dex Receiver and an Android Tablet (via follow/share) in the next room (with me) which works out well and gives me a dual path for nighttime alerts.

Also, I change the Dex Alert levels between day and night. That is one of the tips I picked up on these forums which was incredibly helpful even though it sounded so minor. At night, I want to be (low) alerted if the BG dips down to 100. During the day, I don’t have to be alerted unless it hits 65. It only takes me 5 seconds to change the alerting levels but is HUGELY helpful.

OMG! A blast from the past. I wore one of those monstrosities for half a day, and it did not work at all. My doc had gotten one and was anxious to see how it worked. I was just lucky (?) to have an appointment the day he received it, so I was the guinea pig.

I recall it did not return a single reading.

I am talking more about generalities of sensing through the skin. There have been several companies that tried to create a through the skin glucose sensor for use in physicians offices, so every patient could get a non-invasive glucose measurement every time they go to the office. The hang up is that the spectroscopy required to accomplish this is very computer intensive. So much so that they haven’t been commercially viable. With that said, computing power is always progressing, so the problem will be solved, the question is just when.

The difficulties are that because we have so much H2O in our bodies the window for the spectroscopy to work is really small. In that range oxygen has a primary absorbance peak, which is why oxygen sensors are so common, but the glucose signal is 1000x smaller (second overtone, if my memory is correct) and so it has to be separated from other noise effectively before the product can be viable.


If the doctor’s office version is not ready yet, I am sure the home version is in the very distant future. I know how long it was between doctor’s office BG tests being available, and the home BG test kits first coming out. They have to be able to make it cheap enough for home use, and small enough to be practical.

Kinda reminds me of the flying car:

True, although they might be able to create one today, but not have the ability to charge for the test. Getting a medical device to market is more than just the technology working, the medical establishment has to agree it works, and then the government and insurance needs to agree to pay for it. And testing every patient’s glucose every visit hasn’t been shown to help non-diabetics and so insurer’s and the government would naturally not be excited to pay for this.