Continous Glucose Monitors. How accurate are they?


(Travis_Emerson) #1

The Pump I am currently looking at, offers a CGM. And I was wondering how accurate are the overall. And I here it make life with diabetes alot easier.


(joe) #2

mine too (minimed paradigm 722)  but I don't like the cgm technology yet.  The sensors are set into your skin at an angle to measure interstitial fluid (not whole blood like the finger prick bg monitors).  They need a lot of calibration.  You are supposed to check your cgm reading against a finger prick often and reset the cgm if the result varies.  The readings may be 30 minutes behind reality and if you are dropping or spiking fast... it's just not going to warn you until it's a little late.

If you are hypo unaware then it's the best thing out there.  unless you like doing a blood test every half hour.

I hope for an integrated sensor with the pump infusion set.  I hope for a sensor that is fast, accurate, and real time...  in my opinion it's not ready yet....  but that doesn't mean you shouldn't try it if you want to!

good luck!

 


(Gina) #3

I just started using a CGM a couple of weeks ago and to be honest and I don't know if I am in a "honeymoon phase" but its been working out really well for me.


(A-D) #4

I have had the chance to try the Medtronics Guardian RT and the old and new Dexcoms - the old Dexcom didn't work at all for me, the newer version worked better and the Guardian RT was nearly flawless.  YMMV!!!  I have been on several boards where folks discuss them and it seems  one works better than another for everyone and there seems to be very little consensus - which leads me to believe that everyone's individual body differences play a big part in how well the various monitors may work for any one individual. 

After all the trials, I think I'm hangin' a left and going to try for the Navigator...  My pump uses the flash strips and I use the flash meter anyhow - and the pod batteries are the same as the Navigator transmitter - and well.. it just seems like an easier fit for me.

I am hypoglycemia unaware - but I would say for anyone - it is worth a try.  They don't work for everyone - but from everything I've read - they work very well for many...

Do I do a great job of saying turn left and right at the same time  or what?!?!?!?

Cheers!

A-D

T1DM


(Gina) #5

A-D watchhhh outt!!!! lol I heard good things about the Navigator but I have the MM pump and didn't want to wear another device. So I opted out of that. I am liking it so far I had some errors today and yesterday trying to work out kinks still.


(Payton) #6

Have you guys heard that something from the Navigator remains in your skin after you remove the sensor? This is from Abbott's (Navigator manufacturer) own website:

Warnings/Precautions:

A portion of the membrane polymer will remain in the skin each time the sensor is removed. Although no health effects were observed or reported in clinical studies, the long term effects of the sensor membrane fragments remaining in the skin have not been determined.

This was enough for me to avoid looking at this system altogether. Neither MM or Dexcom have this issue.


(A-D) #7

Payton,

Given the fact that the polymer remains in the skin, the idea didn't really bother me.  I figure the body will likely expell it at some point.  Heck I had gravel that took a few years to work its way out... a clean polymer designed for internal use seems (theoretically) harmless enough for me to feel comfortable with the idea...

Cheers!

A-D

"I didn't have to be diabetic to be abnormal :P "


(system) #8

[quote user="Joe"]

mine too (minimed paradigm 722)  but I don't like the cgm technology yet.  The sensors are set into your skin at an angle to measure interstitial fluid (not whole blood like the finger *** bg monitors).  They need a lot of calibration.  You are supposed to check your cgm reading against a finger *** often and reset the cgm if the result varies.  The readings may be 30 minutes behind reality and if you are dropping or spiking fast... it's just not going to warn you until it's a little late.

If you are hypo unaware then it's the best thing out there.  unless you like doing a blood test every half hour.

I hope for an integrated sensor with the pump infusion set.  I hope for a sensor that is fast, accurate, and real time...  in my opinion it's not ready yet....  but that doesn't mean you shouldn't try it if you want to!

good luck!

 

[/quote]

 

I'm going to make a couple of comments about your post.  Yes, the MM CGM is angled and measures interstitial fluid (they all do).  If it were to measure blood, you'd be forced to wear an IV line all the time.  That will never happen.  You wouldn't be able to insert a line into your own vein each time.

Yes, the CGM requires some calibration, but not as much as you think, and you don't reset it if the reading is off.  My daughter has worn hers for two years now, and we calibrate three to four times a day.  She went from 10 - 12 fingersticks a day to 4 -6...cut in half.  Her A1C is way down, and she has a lot more confidence.

We generally have readings within 5 to 10 points of a fingerstick, often they are the same.  The only time it is off at all is when there is a rapid change in blood sugar, either up or down.  This makes perfect sense because sugars will be in the blood before they reach cellular tissue.  The lag time is only about 15 minutes, however, not 30.  We accommodate for this by setting her low and high threshold to allow us to catch lows (in particular) before they become a problem.  She usually catches them in the 70's now, and she had hypo unawareness before.  We also catch high's before they become an issue and can be more easily treated.  It's also a good way to catch an insulin delivery problem before it gets out of hand.

They are trying to integrate a sensor and site set, but, when insulin is infused near the sensor, it will mess up the readings.  This may never work out unless there is some kind of protection for the sensor.  Another thing, too, is that since sensors don't infuse anything, they can be left in the body longer than insulin sites.  Insulin damages surrounding tissues and so the site needs to be moved every three days, but a sensor can be left longer.  We generally get 10 - 12 days on a sensor with no trouble whatsoever.

 


(A-D) #9

Teresa,

They are working on IR sensors which are non-invasive AND get blood values so, in terms of where things are headed - I suspect it is hard to predict...

A-D


(system) #10

[quote user="A-D"]

Teresa,

They are working on IR sensors which are non-invasive AND get blood values so, in terms of where things are headed - I suspect it is hard to predict...

A-D

[/quote]

You are right, but he was saying he was looking for an integrated sensor with a pump site, so I specifically addressed that.  There are LOTS of things on the horizon, which is very exciting.  I'm sure that in a few years the technology will be simply amazing!    For now, what we have works pretty well, and it's pretty amazing on its own if you figure where things were even five years ago.

 


(anathia) #11

I am on the Paradigm 722, as well. I love that there are no wires, and I wouldn't have done it had there been.

I received this tip from the two women who trained me on the CGM component of the Paradigm: Minimed recommends 3 days, I'm assuming to avoid liability for infection or allergic reaction (skin rashes).  The women who trained me said that yes, MM says this, but that it's okay if you wear your sensor for longer; they said that it gets more accurate the longer it is in, as long as the sensor hasn't gotten worn out.

 

I tried this and discovered that the sensor itself is most accurate after it has been in for four to six days. (It usually loses its accuracy after about day nine on me.)  Apparently, this varies for each person, though.

I'm not saying you should violate doctor's orders or anything, but I highly recommend that you consider trying this.

 

Good luck!


(system) #12

Minimed recommends 3 days, I'm assuming to avoid liability for infection or allergic reaction (skin rashes).

 

It's because FDA guidelines, at the moment, only allow 3 days wear.  MM has a request in for six days, but the FDA hasn't approved it yet.  The Dexcom was approved for seven days.

So, until the FDA approves the longer timeframe, MM is not allowed to say it can be worn longer.  They are aware that the sensor is more accurate later, generally after day two, and there is a biological reason for this as well.


(joe) #13

hi Teresa,  thanks for replying to my opinion, but I am unsure about your point...  so I'll clarify mine a little.

the fact that the cgm uses interstitial fluid is a detriment.  it lags often 30 minutes behind reality. for some super-lucky people it may be less, but there is always a lag.

the fact that it needs a finger stick calibration (okay 4 per day)  is a detriment, too.  I am a process engineer and work with instruments that go 5 years, yes years, without needing calibration.  Often 10 years elapse before an actual adjustment is needed.   Now that's a good instrument. =)

I am glad today's cgm works for your child, and that her a1cs are better, and the fact she is hypo unaware means you gotta make the best of whatever you can and I am sure she is very much better off with some kind of tool to help. Still, the original question was about cgm accuracy, and I was pointing out the issues with today's cgm.  I also have a problem with home bg machines, I don't think they are accurate either, and when I am personally trying to hit between 70 and 100 mg/dl all the time, I don't like a machine that can be off as much as 30 mg/dl. I need >1% and a standard deviation of 1mg/dl or less.   To maintain my 6.4 a1c I need better instruments, MUCH better instruments that what I have available to me today.

I think a lot of development and evolution with cgm technology is needed before I jump on the bandwagon, and I still want one integrated with my pump infusion site (or better yet, completely non-intrusive) that measures actual blood sugar, realtime.  I don't thinnk it should require something as barbaric as an IV tap, and I certainly don't think it's impossible, excluding the current state of today's cgm.  =) and so that was the basis of my opinion, and the purpose of my post.   ...and I also try not to use words like never.

cheers!


(Morgan) #14

I have a pump and CGM, but I don't really like it. It is extremely helpful, but mine doesn't stay in very well. They may not be 100% accurate, but they are pretty accurate. If you're going to calabrate, never do it a couple hours after a bolus because(depending on the insulin), it could be peaking right then and then it would be off. I haven't used mine in a long time, but when I start driving I might use it more.


(Grahamkracker) #15

I am not on a pump nor a cgms..... I looked at the guardian from MM and also the navigator and the dex system..... It looks like the guardian is the smallest of systems...... and it looks a lot less painful to insert than the others........

 

For those who have a guardian from MM..... is the insertion similar to doing a finger stick with the lancet device?????

 

 

 


(A-D) #16

Kristy,

There are a lot of folks with more/better experience than I have in this area - but I've tried the Guardian RT and both iterations of the Dexcom products.  It seems everyone has a bias and for me, the Guardian worked the best.  That said, the insertion is closest to putting in an infusion set and it is not at all like a fingerstick.  You have a needle that introduces the sensor and when you pull the needle back out you are leaving the sensor under the skin.  The Dexcom insertion was, for me, noticeably more comfortable.  The Navigator hides the needle in the inserter which is more my speed (I am scared of needles - great irony, eh?)  that said, Abbott has been unwilling to let me trial their device so I can't speak first hand about any of their components.

Hopefully I offered more light than shadows and I am sure others will jump in and fill in the blanks...

Cheers!

A-D


(Payton) #17

I adore my MM CGMS. I'm glad it is inserted with an angle - I don' have enough fat for it to go in at 90 degrees. Mine is rarely 30 minutes behind reality...I don't know anyone IRL who has one that says it's regularly 30 minutes behind. If that is the case I'd encourage the PWD to contact their sales rep/trainer.

It's usually 10 points within my meter and it catches up within 15 minutes if there is a rapid change. I only have to calibrate 2-3 times per day and I have cut my testing way back - from about 13 times a day to 2-5.

Personally I don't think it's that painful to insert, but I use the silhouette sites and they're pretty similar. It's a lot more....intense than a finger stick though, that's for sure, but once a week is much easier than up to 91 finger sticks a week. My MM sensors are lasting about 7 days.

YMMV....but it's the best thing that's happened to MY diabetes management in years! I love it!


(ruthyhill) #18

[quote user="Kristy"]

 

For those who have a guardian from MM..... is the insertion similar to doing a finger stick with the lancet device?????

 

[/quote]

 

In respect that you have to push a button for the release of the needle (or lancet), than yes they are similar.  HOWEVER, you see the entire needle during the insertion and then you have to pull it out to leave the catheter in.  I don't really enjoy the site of needles being inserted through my flesh (although I've been diabetic for 19 years), and always look away while I push the button.  Also, you need to insert the sensor at a certain angle unless you want to get an extra dose of pain and/or blood... at least in my opinion.

 

Also, in regards to previous posts, everyone is right in their own way.  Yes, calibrations are not too bad.  In fact, you really only need to calibrate every 12 hours.  However, since I've been on the pump with CGM, I do test more since you can't rely 100% on the CGM readings so you always have to verify with a fingerstick test.  I have also not been as lucky as others who state that their readings are almost exact to meter readings.  In fact, sensor glucose readings are noramlly within 20% of meter readings.  For instance, several nights a week my pump alarms me that I my BS is 80 when in fact at times I'm in the mid-high 90s range... or very rarely in the low 60s!  The CGMs are not perfect, but when I think how far technology has gone compared to, lets say the late 80s which was when I was diagnosed, so much has been done to help control our levels and hopefully reduce the chances of complications.

 

Take care everyone!!!

Ruth

 


(ruthyhill) #19

[quote user="A-D"]

Kristy,

There are a lot of folks with more/better experience than I have in this area - but I've tried the Guardian RT and both iterations of the Dexcom products.  It seems everyone has a bias and for me, the Guardian worked the best.  That said, the insertion is closest to putting in an infusion set and it is not at all like a fingerstick.  You have a needle that introduces the sensor and when you pull the needle back out you are leaving the sensor under the skin.  The Dexcom insertion was, for me, noticeably more comfortable.  The Navigator hides the needle in the inserter which is more my speed (I am scared of needles - great irony, eh?)  that said, Abbott has been unwilling to let me trial their device so I can't speak first hand about any of their components.

Hopefully I offered more light than shadows and I am sure others will jump in and fill in the blanks...

Cheers!

A-D

[/quote]

 

OOPS!  I didn't realize someone pretty much said the same thing as I did to answer Kristy's question.  That shows just how much I pay attention :)

 


(misstifyde) #20

My son is on the MM 722 pump, so I got him the MM CGM. He hated it! He is very skinny for his age and the sensor caused too much pain.

So I gave it a rest for about 6 months and when he got sick in August, I started to rethink the CGM. I got insurance to approve the Dexcom and we've been using that now for about 4 weeks. I LOVE IT! I can't say he loves it.. One more thing to poke in his butt, but he really likes that he doesn't have to change it every couple days and he doesn't have to do as many fingersticks.

Also the sensor is far smaller then the MM one and it doesn't hurt him. It takes 15 minutes to calibrate vs. 30 + on the MM.  So although he has 2 things to pug around, we are really getting a lot of value in fiding out trends with the Dexi.

if anyone has children, note they just began clinical trials to get FDA approval for the Dexcom for Peds. the new sensor will be about half the size of the durrent one, which is still smaller then the MM one.

Come to think of it, I'm not sure how I got my insurance to approve the current adult model, since he is a kid......Hmmm