Choosing a CGM

Ok, I have decided to buy one and even use it. I bought one years ago, but never used it.
Could I get opinions about which one to buy?

I have been a type 1 for 60 yrs and have never felt better. I respect technology but am rather a tech idiot. I didn’t use my last CGM once I learned that the results I got wouldn’t match my monitor. Plus I have had A1c’s 4.7 to 5.5 for the last 20 yrs.
I think a CMG might be handy at the gym during daily workouts.

So, I would like a CMG which is non obtrusive and easy to wear, one which gives results which match my monitor. I probably won’t wear it at night, because I always wake up and don’t need my sleep to be more interrupted.

I do not use a pump.

Thanks so much!


I’ve had nothing but bad luck with Medtronic CGM’s. Itchy, irritating sensors that fall off now matter how I tape them up. I had reps out to my home to see if they could help with the issues–mostly issues about gross inaccuracies. Over a year spent using them and untold hours dealing with tech support, all to no avail.

Then I switched to the G5 and it’s been quite a revelation that one product could be so much better than another, in the same space. Wish I’d switched much earlier, but the cost was prohibitive until Medicare covered the G5. Prior to that, my Enlites were partially covered by group insurance. I’d never consider another Medtronic sensor due to the form factor that irritates me, even if they upped their game, accuracy-wise.

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Marilyn, The Abbott Freestyle Libre seems best for your intended use. That’s just my opinion considering you don’t say you want alarms/alerts (which is the main advantage of the Dexcom). I’ve tried both and have no concerns about overall accuracy. The Libre is also less expensive and very easy to use, unobtrusive.

I say all this despite me being a Dexcom G5 user. I want the alarms/alerts and chose Dexcom on that basis.


For many people, the financials are a key factor.

Are you paying cash or going through insurance? Are the financials a factor or not relevant for you?

Perhaps start by listing out the approved systems?

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Last time I bought one, our excellent insurance paid for it. Now that we are on Medicare, but also have excellent insurance I don’t think we will have to pay much. Of course we pay way too much for insurance.

I hadn’t even thought to see which system my insurance company would approve. Thanks for the head’s up. If the system I decide I really want isn’t covered I will pay cash.

Thanks John. The libre certainly looks easy to use and is quite reasonably priced. I will look at the Dexcom just to see what it offers. The libre is certainly less complicated than the CGM I purchased years ago and much less expensive. I can’t think of a good reason not to use it.

Wow, these are now so small and uncomplicated that I will wear it at night, so that I don’t have to get up in the night to test.

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I am on Medicare and G5 Dexcom which is expected to be upgraded to the G6 in a few weeks and then G7 next year. My Dexcom is 100% covered by Medicare. The initial package includes the transmitter, receiver, sensors, test strips, lancets, test solution, contour next meter kit. Every month Dexcom emails a form that must be filled out and returned to them certifying how many test strips, lancets and sensors you have not used. Based on that information, they send you an additional month supply of sensors, test strips and lancets. The supplies arrive Fedex a couple of days after they receive your monthly form. The whole process is quick and efficient. Approximately every 3 months, Dexcom also sends out a new transmitter.

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I think there is only one system that is reliable in terms of accuracy - Dexcom. There is also Eversence, people report good results, but there is not much info though. It would be the best in being non obtrusive, since the sensor is implantable. Libre is nice in its simplicity, but accuracy is sketchy for some people.


And finger sticking to compare.
Dexcom 6 win but by a smaller margin than I thought1

I have been wearing a Libre Sensor for a year now and decided to switch to the Dexcom because it is supposed to be more accurate and has the alarms. I started the Dexcom 3 days before the Libre sensor wore out to be able to compare the two.

The differences

  1. I thought the Libre sensor popped off easy if it got hit wrong, the Dexcom started coming off with my first shower the first night I was wearing it. I am allergic to so many adhesives but can handle Elmers glue which (wears off fast) so I have put that all around it and have wrapped my arm in an ace bandage, They are sending me free over patches to help keep them on. I will have to try the Skin Tac to see if I can use it.
    Note, the the overpatch was as bad staying on as the sensor adhesive. Skin Tac worked great.

Libre win

  1. I love the constant flow of the Dexcom without waving the reader under it.

Dexcom win

  1. I hate the need to keep the Dexcom reader within 20 feet of me to have a reading, If I leave range I have to wait to get a reading.

Libre win

  1. I have graphs on both, I have arrows pointing trends on both


  1. Libre actually catches changes faster, my numbers changed faster with the Libre sensor, is it the 5 mintues delay of readings with the Dexcom? It might be that, no biggy on this though.

No points

  1. The Dexcom has alarms Yea, Uh wait annoying lol!!! I quickly have turned off most of the alerts and set a lot bigger range for them to go off at so they don’t. I haven’t figured this one completely out yet as there are aps that could have given me alarms for my Libre. But the Dexcom comes with them and I actually kept thinking about getting an ap for the Libre and didn’t soooo

Win if it doesn’t annoy me for Dexcom

  1. Because of being able to calibrate the Dexcom, it seems to be more accurate. I say seems to be because I could mostly rely on the Libre, I would finger stick and double wear the Libre Sensors the first day to find out how accurate they were. Then adjust for it. A couple of times they were up and down and those I called in for a replacement, I wanted consistency. Also if they were off by 30 points plus I would call it in as I hated to trust dosing by adding 30 points to my numbers.

But the first day the Dexcom was all over the place, higher, lower, close. With the calibrations I do seem to be keeping it mostly within 5 points now. But it is interesting as I keep reading the Libre and the Dexcom and they are steadily about 25 points apart. And that is what I was basing my dosing on the Libre. I am also finger sticking right now but the Dexcom has had, even with the calibrations, a few more off numbers. I say that as the Libre was off by more but I could count on how off it was consistently. But I will give this to the Dexcom because it is closer to the right number from day 1 with the calibration ability.

Dexcom win

So this is a 3 to 2 win (2 ties) for Dexcom, but it didn’t win by as much as I thought it would? The grass is always greener thing?

And I have to think the Dexcom has to win because of the accuracy factor, that would be mostly because of the ability to calibrate it at the beginning. I’m not sure everyone would double wear or finger test that first day to know the off amounts by the Libre and trust it, then you have to commit to trusting it, so that really is a biggy in the long run. When I was in the endo’s office and showing them the Libre reading 99 and my Dexcom reading 126, both with a sideways arrow, it just shows what a difference it can make. Don’t dose at 99 maybe okay at 126 but I would probably give myself a unit of insulin through my pump for the 126. If I didn’t have an insulin pump I probably wouldn’t dose the 126 either.

Also I’ve had 2 alarms I appreciated, One was a high alert after I had gone to bed, it turns out that right before I changed my pod and had programmed insulin for a snack, I didn’t get that insulin. I noticed when I took off my pod there had been leakage and hadn’t thought anymore about it. So I was able to give myself a dose so I didn’t wake to having a huge number in the morning. Plus in the morning I was hanging out around 70 when I have usually started to skyrocket by then and decided to drink a little OJ. Of course about an hour later I started my skyrocket anyway!

Now why can’t it just beep once and you can stop it after that? Because when it hit that high I kept getting beeps, as my BG’s kept going up until the insulin worked. Like I said some of it is annoying!

PS A couple of added notes
The Libre numbers on the reader are bigger, black on a white background and much easier to read. I noticed this in the middle of the night when I was trying to focus and read the Dexcom’s reader.


Thanks so much Marie. That was a very detailed report. I appreciate the time it took you to write it.

Since you are covered by Medicare the Dexcom would be a good choice for you. There are inaccuracies with all meters and CGM’s when compared to lab blood test. You should talk with your doctor and have him/her provide you with more information.

My doctor depends on me for advice about diabetes. I don’t think he would have a clue about a CGM. I don’t go to an endo. The only time I did, he said I was doing great and sent me on my way. Once you have had diabetes as long as I have, 60 yrs, and have no neuropathy, kidney problems or retinopathy doctors actually don’t have much to say.

I am definitely going to check out the Dexcom. Thanks for the vote Don.

Hi Marilyn,

Your A1c’s are awesome! I’m not sure if you’re looking (or need) to improve them.

The reason I bring that up is they have found that A1c improvements with CGMs are proportionally larger if your A1c is higher is to start. So, keep that in mind, expectation-wise .

What I’ve found, having recently began using a CGM (Dexcom 5, for about 3 months) is that the convenience is where the huge gains are made. Also, I’m able to eat the “bad” stuff and control it to a much, much greater degree than with finger sticks.

And exercise is a whole different world with the CGM. I simply wouldn’t do cardio if I had recently dosed. Way too much risk of a hypo. With CGM, you see a rapid drop coming a mile away.

I don’t know how other CGMs operate, but you can’t pull out a Dexcom at night. But I don’t really notice it when I sleep.

Good luck!

What a thorough comparison! Thanks Marie.

Thanks Kelly. I just thought I would try one for the convenience. I am not really interested in lowering my A1c, but wouldn’t complain if that happened. :grin:

5.5 is great. The closest mine has been to that in the last 6 months is 5.7, thanks to pumping, and my G5 (and wisdom gained from fighting this disease for 40 years). As long as I’m under 6.0 I’m happy, and I don’t expect to ever see it fall below about 5.7.

Pumping (and a CGM) are two AWESOME TOOLS for us active diabetics. Go for it!

(Not that they aren’t also great for less active)

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The lowest cost and low learning curve to be up and running, is the freestyle Libre, since you said you don’t want alarms. Libre is now covered by medicare.

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I don’t understand why a T1 wouldn’t want alarms–maybe they are so well controlled that they don’t fear for their safety–which begs the question–why get a CGM if that’s the case? Me–I need both high and low alarms.

Dave, I am extremely well controlled, and rarely fear for my safety. I was on a hike last summer, and because of unusual circumstances, I didn’t eat enough and ended up laying in the path with my husband feeding me dates. In my 60 yrs of diabetes I have only needed help a handful of times, and have never had to go to the hospital for my diabetes since I was dx in 1959.

With a GMC I will be automatically checking it anytime I find myself in an unusual situation. I spend a lot of time at the gym. It would be handy to just check it instead of getting up off the exercise bike and testing when pedaling becomes difficult. I always wake up if I am low in the night. I am very, very fortunate. I will be obsessively checking the GMC, just like I obsessively finger test to catch any highs.

I am getting one simply for convience.