More Dexcom G4 troubles

SO far, used my first infusion set successfully, then when putting in the second I had a bleeder, so I put on the third one then my 4th one had a sensor failure due to a lovely DKA was unwelcomed. I never did get the replacement of the 2 despite trying to get a hold of my rep and with voicemails that I couldn't even make out but heard tech support and dexcom after requesting from my rep to have them email and she would make sure they would.

So my new box arrived. I put in the first one and thought yay no issues lets go for week 2. So, today, I checked my sugar level, it was 360. SO I checked for keytones, nope, gave myself the insulin, and did some house work which brings down my levels. SO it started to come on down I am like yay! it was at 353 when it was working its way down. Then it stayed leveled then it had the arrove pointing upwards to 375..Um yeah that doesnt sound right. So I checked my sugar levels and it was 255. And yes I calibrated it correctly this morning too! So my average is a week for each sensor :(...with the dexcom 7 I never had this many issues within a month. Am I the only one who has not so good luck with this? My pump has failed on me as well.

I am hoping I'll have better luck with this box (ok with the one I have on and the 2 remaining)

I’m very new to the Dexcom in general (just started a month ago, my first CGM) but one thing I noticed is that you shouldn’t ever calibrate if the Dex is showing an up or a down arrow, even if it’s asking you to calibrate. Only calibrate when it’s showing you a flat line and you know your sugar isn’t rising or falling. I had a few problems with wonky numbers on it when I didn’t follow those directions, and it’s been a lot better since.

You may already know that, but thought I’d throw it in there. Before I was calibrating every time I tested, and that just didn’t work. Now it’s pretty much only when it tells me to calibrate or it’s off by 20% or more.

it was time to calibrate the monitor anyways. It was steady when I did calibrate it. Then it went down then up.

Sorry to hear that :/

Like I said, I'm brand new to this so I don't think I can help you any more than that. Good luck, and I'm sorry it's been so frustrating for you. The G4 has been an amazing tool for managing my diabetes so far.

So far, pretty good with mine. I’ve botched installing two infusion sets, but I’d say they were my fault. Seems a bit tricky to install the sets, but I suppose I’ll get better at it.

I know there’s a way to extend the 7-day life of the set, but I don’t know how and am just replacing them at the insistence of the meter. It does seem to grow less accurate about the seventh day.

Otherwise, accuracy seems good, but doesn’t go over 400, which happened a week ago when something went wrong with an Omnipod pump. Usually its reasonably close to the Omnipod meter.

Have had good results in terms of hypo alerts which is good as I don’t notice until I get to around 20. Definitely close enough to check when I get in the car. Cannot necessarily hear/feel the alert if I’m mowing the lawn. I bought the armband from the company linked to the Dexcom site so I have the meter with me if I’m exercising or outside.

I’d definitely say that I already missed it the one time I was without it for a few days.

My wife loves it as she can take a quick look and nag, I mean, um, help, if I’m too high or low.

In the end, I guess all the technology is good, but you still have to check on things, etc. since any of these devices can fail.

"Extending the life of the set" is as simple as just leaving the sensor where it is, and when the receiver prompts you to replace your sensor you just say "ok" and then press "start sensor" without actually changing anything. It doesn't know the difference between the sensor you still had on your skin and a "new" one.

I've never been able to do it as the adhesive always starts to peel around day 7 or 8!

I am a fairly new G4 user. I did a lot of research on it (and continue to, CGMs in general).

The G4 is probably the best CGM available right now. However, there are a few caveats with any CGM that always need to be considered:

  • A CGM measures interstitial fluid in the subcutaneous tissue, not direct blood plasma. This results in readings that are on average about 15 minutes behind your plasma values. If your BG is changing, the G4 reading will never match up with a finger-stick. The faster it's changing -- indicated by the trend arrow on the G4 -- the wider the discrepancy between what the G4 is indicating vs. what a finger-stick tells you will be.
  • Dexcom deliberately engineered the G4 to have its greatest accuracy at the low end, to more precisely catch hypos, which are a much greater acute risk. This sacrificed accuracy at the high end, so the G4 gets increasingly inaccurate above 200-250, especially when BG is on the move. Do not rely on the G4 values directly for anything over 200. Treat it instead as simply an indication that your BG is high, and needs to be treated. Calculate dosing based on a finger-stick (accurate) rather than the high value the G4 is telling you (relatively inaccurate).
  • This bears repeating: Do not calibrate when there is any rising or falling trend. Only calibrate when you have a flat trend, with a right-pointing arrow.
  • The 15 minute delay in the reading is hard to wrap your mind around so you relfexively look at that display and interpret it as an old reading. It's natural to look at it and think, "that's what I am right now". But you're not. That's what you were 15 minutes in the past. Consider a reading of 135 with the double up arrow trend (default setting for that is 3mg/dl-min change). That means that, assuming the 135 is fairly accurate (which at that level it probably is), your actual, current BG is around 135 mg/dl + 15 min * 3 mg/dl/min = 135 + 45 = 180. Yet, if you have the natural tendency to look at that 135 and think, "I'm 135", you're waaaaaayyyyyy off, really being around 180.
Correctly interpreting CGM numbers is not straightforward. Correctly interpreting trending information is. Use your G4 to help you avoid highs and lows, but don't place too much confidence in the actual, raw BG value displayed.

Also, remember that there are two delays you have when dosing fast-acting insulin, and seeing the impact on a CGM. First, there is the delay from absorption. Then, there is the 15 minute "always behind" delay with insterstitial fluid to catch up to BG.

So, after administering a correction, either as an injection or via pump, you won't see any effect for at least 30-60 minutes on the G4. Be patient. As long as you did a finger stick and calculated your correction bolus based on that, BG will start to come down. If, after 2 hours, it doesn't seem to be coming down enough, then you can correct some more. But, you gotta give the whole system time to work.

Not trying to nitpick, just honestly confused... You refer to "infusion set" above, but I think you're talking about the sensor wire, right?

Just so we're all clear on what we're talking about...

Have you tried Skin-Tac, and placing on the back of your arm? I'm having truly excellent results that way. I'm on day 10, with nary a peel-up at all.

Granted I haven't done anything rigorous, but just carrying on with work, family, etc.

For me, Skin-Tac made all the difference. My first sensor started to come loose on day 4. By Day 7 despite taping it and so forth, it finally just cam completely loose and failed.

Skin-Tac is like epoxy on my skin. Keeps the G4 and the Omnipod firmly in place.

Hmm, I'll have to give it a shot. I've never used Skin-Tac for anything. I've never had a problem with Pods coming off - the adhesive has always been fine for the 3-day life of the Pod.

My educator told me and I've read online that you have to be very careful to not let the sensor go into a spot of skin where there was Skin-Tac cause it can mess with the readings. Is it hard to position it so that the sensor doesn't go through the Skin-Tac? Like wiping in a circle around the insertion spot or something?

I do intense workouts 5-6 days a week and the adhesive has always stuck for the 7 days on my abdomen, but I'd love to get more time out of it!

I've been told no such thing, and I've had excellent performance with my sensors punching right through that layer of Skin-Tac.

So, I can't validate your CDE's advice -- I'm having the opposite experience.

If you want to give it a try, report back to the rest of us what happens!

I dont know if I have skin-tac I would have to look. I guess I can look at amazon and see what it looks like so I can say oh I do have those

I am on the pump and CGM so I am switching all the time and forget oh its this I need to refer to. The sensor is what I meant

I do check when I see the CGM do something odd. I learned never to rely on the CGm..Ive seen a few people not checking their sugar levels and go by the CGM. I just shake my head

Mine starts to peal off at 6-7 days… I work out about 2 hours x 6 days a week and take long hot showers after so by then the adhesive is “shot”…after 6-7 days I first shave the area around the sensor, clean 2-3 times with alcohol swabs ( gets rid of oils and dead skin) , then apply mastasol… Let it dry then apply tegaderm ( usually one cut up in pieces to go around and cover DEXCOM adhesive and the skin around it ) … Works well for another 5-10 days, by then I don’t care and remove sensor for a new one ( insurance pays so not much incentive to use longer than 7 days except convenience, avoiding Day 1 errors , and avoiding mild pain of inserting new sensor). Good luck!

Hi Amy,

I am only on my 2nd sensor, but I'm getting to know it pretty well, and the results are acceptable. As someone already remarked, the levels may be off on the 1st day, and from thereon, their shouldn't be any issue. So hang in there, and the sensor may settle.
I did one week with my 1st sensor, 3 with the second, and will be going into the 2nd week with the one I have now. The results are excellent for me, although I have no experience with levels as high as yours. 200 is about the highest that I may get, and then very rarely. You are of course in charge of yourself, but you should really try to avoid these sky rocketing numbers. They are not good for you !!!

Thank you. You are fully correct. But, take the times with a grain of salt. The time depends on the place of insertion, and if accidentally you are in a belly muscle, then changes come through fast.
Last week I suddenly dropped like a rock. G4 gave me 47, glucometer gave me 43.

Ugh…I got the three ? marks and read in the manual what it means…once it had a signal.i out in the bg…so all was fine and dandy until I checked my sugar levs this morning instead of the 173 that the cgm says I was so tired that I calibrated at the 219 my meter was telling me…not even two seconds tee it give the blood symbol to calibrate it…again I was so tired for checking the cgm to get out of the ??? meter said 249 so I entered it said 179…now at 10:10a my time it caught up to where it says 233 >_<…sigh

Things will be better with this thing right?

Thanks for the advice! Sounds like a bit of an elaborate setup but works. Another issue I seem to have is that by day 7-9 it is often kind of itchy anyway so I don't feel comfortable leaving it on longer. Maybe it's psychological, but it just seems weird to leave a sensor in your skin when it's causing irritation.

I've heard about the possibility of Skin-Tac fouling a Dex sensor if the skin sensor passes through a patch of skin coated with Skin-Tac. I'm not sure I believe that but I haven't taken the time or effort to do the experiment. It could be true.

What I do now is to insert the Dex sensor through clean and dry skin. After I press the adhesive firmly against my skin and after the sensor's been inserted, I apply the Skin-Tac to the top of the adhesive fabric. It soaks through and I can dependably get 14 days out of a sensor with little adhesive pull-back.

I find that the sensors generally have great correlation with my finger-sticks during the early part of the second week.