Why CGM, really?

I really want to start cgm. But when I read the posts here and elsewhere, almost everyone says that no cgms are accurate for highs and lows. I don’t need a cgm for BG ranges 70 to 160. It seems to me the real need is for accuracy for lows and highs. The manufacturers get away without solving that problem, which is the real diabetes need.

What is the point of having a verification that you are within a reasonable BG range when your finger stick tells you that? And, you can’t trust cgm warnings for low/high readings.
And, you go through a lot of maintenance and hassle for normal range backup info. Perhaps most importantly, many of you still do the same number of BG tests, or more, as you did without the cgm.
Can anyone explain away the contradictions I see?

Well lets start with A1c - personally first month went from 8.8 to 6.8 I like the trend patterns to help understand things like the basal rates, theCarb ratio and the correction factor. The graphical picture is able to show patterns that are important insetting a pump correctly. Itis generally pretty accurate and when it beeps an alarm of alow, you can be pretty sure that you are really low, but to be “by thebook” you should check with afinger stick tobe sure before treating.

I don’t have a CGM, so I’m not speaking from personal experience. But something I’ve heard a lot of people say is that it’s really useful for those trend arrows that show if you are trending up or down (and two arrows means a steeper trend). This is something a lot of people find useful. For example, if you test at 90 before bed, it would be valuable to know if you are trending steeply downward or are staying steady so you can avoid a bad low in the night. Having an absolutely accurate number is probably not reasonable to expect.

Yes, but if the trend arrow is wrong… It may say 30 but your BG meter says 70. Which to believe? For me, I believed the meter. So, then you have to deal with getting the darned thing to stop beeping at you at 4 am. In my one week trial, it beeped me awake 3 mornings in a row. I had to eat way too much to get the darned thing back into normal range - at least its normal range. I wasn’t shown how to turn the beeper off.

sounds like a MM - there is a specific sequence to shutting off alarm on the MM - The dexcom is more accurate and also easier to reset alarm and also has a snooze to the alarm so tat it willnot continue once it has been acknowledged. I havenever seen that much error on my Dexcom,but if I wasat 70 at 4 am iwould want to know the trend and would probably treat with a few carbs.

I wonder if your accuracy experience is typical. Not according to many posts I see. Right now, my A1c ranges from 6.3 to 6.8. However, my BG ranges are from 20 to 600+. Given my A1c, I may not even qualify for a cgm. You are correct in questioning whether I am ready for such intensive focus on my diabetes. I ask myself that too. It takes a lot of focus as it is: BG tests, pump insulin supply and battery OK before going out?, pump changes, supplies, how much to bolus for this food or how handle activity, etc, etc. The cgm will add another huge level of effort. My question was directed at the value received for the additional effort on my part. Cost/benefit ratio!!

Thanks to all responding so far.

If your A1C is good (peeks, ok it’s pretty good!! Way to go!!), I think that a CGM can be useful to reduce the Standard Deviation and gt rid of the 20s and the 600s? Like John said, w/ a CGM, you can spend a lot of time in a decent range. I will watch my post parandials go from 115 to 121 to 125 to 127 to 128 then reach the “crossover point” and come back down. If they are rocketing up, the 128 might reflect a BG reading of 140-150 w/ the “lag time” of the interstitial fluid but, I figure the “crossover point” is pretty reliable. That way, instead of waiting 2 hours to discover a 150 that I would want to fix after the fact, I can check at 128 and see whether that’s the “peak” or not and get a slightly tighter control of that number that way. Similarly if you have any type of DP issues, you can get very nice readings to suggest where you might need a basal bump to help that out, without doing middle of the night testing. Not a huge deal but nice and again wiping out some of the work and suprises? It may seem like a lot of work but knowing pretty much all the time about where your BG is is very useful.

I think that for me too, it’s sort of a reminder that if I have handfuls of junk food here and there, I will see exactly what happens and sort of “upset the apple cart” and I get sort of attached to nice readings so I eat more conservatively. Obviously, a 43 year old shouldn’t need a $7000 babysitter but well, it has had an effect along those lines too.

It’s also very useful for exercising. Not just during but getting ready, making sure everything is smooth and where you want it to be and also after, to perceive and react to post-workout highs that can crop up. You can catch them with a BG meter and, a lot of times, I will double check the CGM but much of the time, it’s very helpful to have live, or live twenty minutes ago, telemetry.

"A survey of adults with Type 1 diabetes revealed that people most likely to stick with RT-CGM are those who can cope with frustrations dispassionately, use retrospective data analysis to correct their mistakes ..."

Continuous Glucose Monitoring Only Successful with Knowledge and Support

I came across a lot of studies which show that 'patient selection' is a critical success factor for CGMs. It would be intuitive that diabetics with the highest A1C benefit the most. This is not the case at all. These diabetics don't benefit at all. The reason given is that these diabetics don't care to begin with and a CGM does not change their attitude.

The last 2 days I lived with an inaccurate sensor. This sensor pushed me past my frustration threshold. If inaccurate sensors were a frequent occurrence then I could see myself giving up. Fortunately this is not the case. Typically I prick my fingers only twice a day. This is how accurate my dex is.

Yes… this kind of frustration… is what you need to be able to just “let go” of :slight_smile:

CGM is great when it works… I use it mostly for trends (in lieu of basal testing for example, I can simply watch the graph to see if my basal is too high or too low, or of my meal boluses aren’t quite bringing me back into range), and catching lows. Clearly it’s not a fingerstick replacement, and it does come with some downfalls… like when it’s nothing even close to accurate!

It’s simply another tool - it’s not a solution to anything specific.

Wow I have never seen that much error - what did dexcom say when you called them - calibration issue? Old sensor pastuseful life? Just curious - the engineer in me always wants to know why!! Did it gradually goi bad or all of a sudden?


For my insurance company my A1c is not the determining factor (obviously they are all different). Their stand is if you have type 1 and have documented blood glucose of under 40mg/dl they will approve, so before you exclude yourself based on your good A1c I would look into what your insurances’ policy (if they have one yet) is on CGMS.

There is no doubt the CGMS puts a more intensive focus on the DM. My experience was that although it was there I did not mind it simply because of the extra layer of protection (for both high’s and lows) gave me piece of mind so in the end the net effect was less worry about the whole process despite the extra wire sticking into me and everything that goes with it.

If you are having bad numbers from your current trial (not sure what you are using) I would suggest trying the other system. Some people do better on one system vs the other.

That sort of study seems like a complete waste of money. “A psychiatrist who studies barriers to the technology”? C’mon Sherlock, let’s see…the disease sucks, medical providers don’t exactly have a constructive plan other than “here’s an Rx, take care of yourself…” and the fanciest gizmo you can get is not exactly accurate and requires you stick a big needle in you every few days and then tape a gizmo to your body. Ya think those might be barriers? Of course that is without all of the organizational barriers of having a medical industry ill-equipped to help people and hamstrung by ridiculous barriers put in the way of the devices by insurance providers and government health plans. It is amazing there are as many of them in circulation as there are.

well glad to see you keep a positive outlook on the struggle with diabetes.No all the barriers are not the medical profession and the insurance companies. Sometimes we the patient are the impediment and what is wrong with trying to figure that out. Hopefully some day they will have a treatment that will reguire less compliance by the patient but for now compliance and education are critical. In order to better utilize the resources that we do have, it is good to know what affects successful treatment so that we dont waste money on unsuccessful treatments.

If you don’t have a positive outlook, the disease is going to win.

If you want to give it a try Gary Scheiner offers a one to two week trial. http://integrateddiabetes.com/cg_trialserv.shtml I’m planning to give it a go and see if its usefulness to predict when I’m going too high or too low to allow me to catch it before the damage is done is worth it.

First of all people rarely post on internet forums when things are going well so things you hear from others are going to be skewed to those having difficulties making it seem worse than it really is.

I’ve experience with both Medtronic and Dexcom CGMS and both were valuable in detecting lows and highs. The Dex is more accurate at the full range of blood sugars I experience whereas Minimed may have read consistently 100 to 150 points lower for high blood sugars. The thing is it doesn’t really matter if your blood sugar is 200 or 350 both will need a correction and having the CGMS alert you to the trend earlier than a fingerstick would is helpful to me. I have always always always found the trends to be spot on with the exception of a dying or bad sensor. Both systems were accurate for me with lows although Dex is faster for me.

I would occasionally get false lows at night if I was laying on the sensor or was dehydrated. Minimed was more prone to this than Dexcom is for me. After a while you’d get so you could tell the difference between a real low and a false one. Usually with false lows rolling over or getting up to go to the bathroom it would right itself. Also I learned where not to put the sensor so I’d be less likely to lay on it.

The number of fingersticks daily hasn’t changed all that much for me since using CGMS. What has changed is when I test. With fingersticks I test on a preset schedule or if symptoms or circumstances that might cause a high or low warrant = blind testing and random chance that I’d actually hit my highs and lows with fingerpokes. Now I let the CGMS tell me when I need to test and it’s not necessarily according to when I eat my meals or the clock. This means earlier correction of highs and lows hence more stable blood sugars overall. Works for me.

Exactly, nicely put!

His site does not tell you the price, however! It says: "A 1-2 week rental of the system of your choice (Dexcom, Navigator, or Medtronic)"
I had a one week trial last summer via my endo office but it was the worst possible time with some family illness issues. The Dex worked ok even with me dealing with travel and other things, amazingly. But there are issues - beyond the ones I have already mentioned. Finding a second site all the time, for one example. I think so far, the issue of cutting down on the extreme numbers is probably the most compelling reason for it.

I dunno if people “rarely post on internet forums when things are going well”…there’s lots of “my A1C improved” posts, Flatliner’s Club, and other good things too? :slight_smile: