So I’ve been generally really happy with my G5 CGM and certainly wouldn’t want to be without it. But it TOTALLY let me down today. I sing in a church choir on Sundays and even though I’m a practiced and expert singer, there’s apparently enough public performance anxiety involved that my BGs always run high due to the adrenalin response. So I always keep a close eye on my readings and frequently bump up my basal 30-50% over normal for a couple of hours. Didn’t have to do that today because my CGM told me I was fine–low 100s, rising slowly to teens over the morning. So a bunch of us go out to a restaurant for lunch and given the decent numbers I’ve been seeing all morning I was figuring I might get to have a few fries with mine. Out comes the fingerstick just to do a sanity-check before bolusing and… GULP! I’m looking in disbelief at 207 on my BG meter. Tested again, different finger, and that’s confirmed: 210, and meanwhile my cgm is happily informing me I’m at 123, almost 100 points off. I haven’t had an occlusion warning or anything, but can only conclude I must have dislodged my infusion set. Went to the Men’s room to check it and the adhesive had pulled free along the top edge at some point so I think it may have gotten yanked getting in or out of my car (trying out a new location on my lower back).
Anyway, the fact is that I’ve clearly not been getting adequate insulin all morning long, my BG has been climbing well out of acceptable range and my CGM has given me absolutely NO indication that this has been going on. This is exactly when having a CGM is supposed to prove its value, even be a potential life saver. I really don’t get how or why it didn’t pick up on this rise, which must have taken place over the four hours or so since I’d done my fasting a.m. fingerstick, a perfectly acceptable 90. I’m very disappointed and what’s worse my faith in this piece of technology that I rely on in a pretty non-trivial way has been cracked. Unhappy!
I agree with @rgcainmd: call Dexcom and get a replacement sensor. I did this last week because my sensor had been consistently off. This is also why I continue to test 3-4 times a day rather than relying solely on the Dexcom.
I understand your disillusionment. The Dexcom system can be so good for so long that you rightfully entrust your life to it – literally. I’ve lived your experience this morning a few times. It’s hard because the Dex system has earned your trust and when it lets you down, the disappointment hurts more.
I know everyone wants to completely trust Dexcom CGM technology, especially since it appears the FDA will probably soon grant it the authority on which to base treatment decisions. We as people with diabetes need to treat that FDA blessing with caution.
Here’s my position. No technology is 100% dependable. The Dexcom CGM operates in a changeable and chaotic environment, both our internal metabolism and the external busy life we live. When it’s really important, when the stakes are high, like when I decide to drive, then I look for confirming fingersticks to better inform me.
I still fingerstick about eight times per day, down from 14x/day a year ago. Your tale reinforces my judgment in this regard. When you use insulin to treat diabetes, a streak of skepticism is a good thing.
Sorry it happened to you. For these kind of things, the bottom line is just to get through it and survive; that’s no small victory.
Remember. Dexcom is just a tool. It is too easy to blindly rely on it. My fear is when/if it is 100 pts off in the other direction… I’ve often wondered if the battery were made to only last as long as the sensor–the whole rig could be a lot smaller. Then maybe multiple sensors could give you better data.
Well, that’s the thing though: I’ve had erratic sensors before, but I’d had this one going for more than a week and it gave every indication it was acting normally, tracking within the usual ten points or so of finger sticks (I still test 4-8x/day, that’s why I caught this error). That’s the part that has me concerned. It had been behaving perfectly normally through exercise, Thanksgiving carb intake, etc. As far as I can tell it was a perfectly ok sensor. Once I recalibrated it, it alerted me I was high and tracked sensibly after I swapped out my infusion set and administered a correction (I didn’t change the sensor because I wanted to see how it would behave). So that’s the disturbing question: could an otherwise functional sensor totally fail to alert me if I had a similar pump failure overnight? Apparently the answer is “yes.” Has anyone else seen something like this?
Hi DrBB, I am not sure if I missed something in the post, but if your sensor was on more than 7 days, that might be part of the problem. I know we all go over the 7 day limit sometimes. The most I have done is 10 days, and it starts to flake out even worse at that point.
All, that being said, I have a bunch of examples where Dexom was so far off it was ridiculous. I frequently see 100 point differences, even if I have followed all the rules. At this point, I can’t see myself trusting CGM to make decisions about insulin delivery in any kind of automated way. That’s just my feelings, I know others are aboard with doing it.
Yeah, it did occur to me that that’s the cause, which is actually part of my concern. I’ve kept them going far longer without any apparent erratic behavior–usually the limit is adhesive failure rather than flaky readings. But it is a question for me now whether something like this could be a hidden risk with rolling over to a new session on the same sensor. It may seem to be acting normally but could be glitchy in responding to something like this. To me it’s not so much an issue of saving money as that I just hate having to change the darn things. But I may have to reconsider the practice.
No matter what day it is, I get odd results, especially when exercising. I would be so leery of letting that thing decide changes to my insulin delivery!!
Any prospects on the horizon for a CGM that actually checks your blood instead of your interstitial fluid?!?!?
