In the last 2 days I have gone through 6 dexcom sensors and have yet to get an accurate reading… 50+ points off from my meter readings every time I test…constantly saying “calibration error” recalibrate at (x time). critical low warnings when my real blood sugar is 110 I’ve gone through about 75 test strips re testing and calibrating (wayyyyyy more than i would need if I was just depending on test strips alone) sensor # 6 is currently warming up will see how that works…submitted a request for replacement to dexcom doesn’t get my last 2 days back…i shouldn’t have to spend all that time…dexcom should save time and the commercials that say “i don’t have to poke my fingers anymore” BS OK rant over
Tim
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Totally understand the need to rant! Sounds like you got a bad batch of sensors. So sorry!
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I have one box of 3 left from the same lot # not feeling good about their potential 
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How long are you letting them go before pitching? I know for me the first 12 hours can be really bad.
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first one was over a day, another was over night and to about 12 hours, one failed immediately, one took a few hours before it totally stooped. I normally get irregular readings for the first 12 hours but nothing like this…so far off, over 50 points and up to 100 off, and when it is that far off and you try to calibrate it doesn’t like it and gives an error and do it repeatedly and it just doesn’t work anymore , at least that is what happened here
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update #6 has gone through the warm up and is giving reasonable readings
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I’m a big long-time Dexcom fan. I almost always have consistent reliable readings. But strangely every once in a while I’ll have a series of 2-3 right in a row that either totally fail or are too wildly inaccurate to use. Different lots and packages. I haven’t been able to figure it out. It’s unsettling and takes a couple days to get back into a normal confidence level and to stop checking it with finger sticks. It’s especially concerning since going on CIQ where algorithms depend on readings.
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I am also a fan …no problems until now for the first 6 or so months I have used it…but glad to hear that it sometimes happens to others as well…actually not glad others have had problems but glad its not only me . the 6th one might be the charm for me…it seems to be doing ok so far at 6 hours going…still not accurate enough to trust but getting better after a huge jump for no reason about 8:30
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update…blood glucose reading 55 … dexcom says 85 good thing i can feel lows
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Those readings look very similar to mine. I’m glad they seem to be leveling out for you. Sometimes the first 8 hours or so I will get weird results but this is day 6 and the up and down jumps aren’t typical.
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those ups and downs sure can be frustrating, safety requires an accurate reading to properly determine insulin doses … had another big jump and a drop, that weren’t real, last night . but the overnight seemed pretty stable
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@3cTim Sorry you’re having the problems stated. I think most of us get somewhat wonky readings the first 12-24 hours. I’ve only been using G6 for about a year now, but can count on one hand the sensors that have been good from the start; most even out after that initial period. But the confidence mentioned by several is critical to all of us and soon most all pumps will be dependent on the readings! While I know the tech has reliability limits, failures, particularly a series of them like you’ve experienced, decimate confidence and trust. At times like these, Dexcom’s customer support is critical, but being shipped off-shore to folks that only read script doesn’t help. Don’t get me wrong, I hate the thought of going back to finger sticks and meters that can have 20% variance, but the failures/rates I hear about and experience give me pause when thinking of becoming reliant on a pump that depends on the data provided.
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I agree with that, rarely have had any problems until this batch, and always do have a really jumpy first day on a new one, (but not like these, with readings off 50 -100 and 2 failed before warm up) but I was really looking forward to the next gen omnipod that will work in a loop with dexcom, but given unreliable recent dexcom data I feel somewhat hesitant
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It totally depends on your current level of success in managing your BG and your expectations of the automated system. If you are thinking that the automated system will take over the job and manage your BG for you, well, maybe it will if your A1C currently is over 9. You’ll likely get better numbers and be safe; the clinical trials showed the systems are safe and effective.
If your A1C is 6.5 and you are on a manual pump, it’s helpful to think of the system like cruise control for a car. First they made cruise control maintain a constant speed. Did it help? For long distance driving it helped some. Then they improved cruise control so that it would slow down to avoid bumping into the car ahead. Was that better? Yes, of course. It doesn’t guarantee freedom from rear-end collisions, but it certainly increases safety and reduces the driver’s effort. They keep making it better, but still the driving remains a cooperative activity between car and driver.
Same for closed-loop pumping. It reduces the burden on the person wearing the pump, because the closed loop is always trying to do the right thing. Among other things, that means it’s possible to sleep through the night while the BG stays in a good range.
Now let’s deal with the “bad sensor” issue. Suppose the CGM says 100 but your actual BG is 50. In this case, closed loop behaves the same as a manual pump. It’s not jamming you full of insulin or anything, it’s just that in case of faulty BG data it’s not actively helping by suspending the insulin delivery. In any case, it’s not taking action that threatens to kill you any more than a manual pump.
Suppose the CGM says 50 but your actual BG is 100. The closed loop will have suspended insulin, your CGM will be screaming, and maybe you will take some glucose. The consequence? Maybe your actual BG will rise to 150. That’s not killing you.
The analysis of 100 vs 150 has the same result. Even if it’s not always 100% helpful, it usually is, and anyway it’s not dangerous.
The CGM errors mean that the closed loop isn’t helping, but it’s not particularly dangerous. And if you are manually responding to the CGM alerts by looking at the graph, you can see (a) whether the graph looks trustworthy or not, and (b) if there is a sustained trend away from a good BG level so you should take action with with glucose or insulin.
The closed loop really does reduce the burden. It’s not fully automatic or perfect, but if you’re willing to cooperate with the algorithm, you can get a good result with less work than manual pumping. That’s my opinion, anyway.
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@bkh Thanks for the perspective and useful examples. I’ll have to re-read and think through them to more completely understand, but they sound logical on first reading. Perhaps my perceived concerns are off. I’m fortunate that so far my TIR is great (70-90% consistently) and GMI/A1c is reasonable. I’ve been MDI for a year (since dx) and understand the manual back-up method if concerns/reality collide and are needed or I find pumping isn’t for me. Thanks again for the feedback!
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I did MDI for 8 years before pumping. My A1C was in the mid-upper 5’s but it turned out to be a combination of long-duration lows overnight and prompt treatment of excursions high. Eventually, the variation in basal requirements night vs day became a nuisance: either I had to tolerate waking to treat highs all night long, or I had to eat all day to deal with the excess daytime basal. Maybe I could have made MDI work if Levemir were available back then, but the pump seemed like an easy way out. It is nice to always have insulin and CGM right there with me (in the pump) without having to carry them as separate supplies.
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another update
got an email confirmation from Dexcom, they are replacing the defective sensors, and sensor #6 while still not totally accurate on day 2, is now within 20 points up or down which is more than id like but i can live with
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This is a very good summation of CGM/closed loop systems. And I agree that it is where we are at this point in time. And weighing all of that I am way better off with and grateful for it all. Especially coming from a perspective of having T1 in the 70’s. I think an important aspect is each individuals biological differences. I am very insulin/carb sensitive so it is amazing the algorithm can keep up at all! On the down side - even a fraction of a unit CAN become dangerous very fast. But like you said, because of this I am always interacting with the closed loop. It is not a turn it on and go thing. But every tool can help and I am grateful.
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I was using a G6 recently and found, just like you, that they were quite unreliable and inaccurate. While wearing the Dexcom I continued wearing my Abbott Libre (which has always worked well for ME). I quit using the G6 and now use only the Libre. As they say, “everyone is different”. I DID, recently, have an A1c of 5.0 and suspected that it might have been a “lab error” since my results have normally been in the low sixes.
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Welcome to FUD @ntrubov! How many sensors and which placements did you try? Thin people have always had some trouble with Dexcom, but some spots are better than others, and most don’t use it in the suggested stomach area. My son uses the backs of his arms, but that spot doesn’t work for everyone.
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