I'm outing myself: Contrary to stern advice from Dexcom, fellow Tudders, and well, myself (past postings), I do make treatment decisions based solely on the data from my G4.
I didn't used to. I started to about 4-6 weeks ago, a little bit, then more and more. Now, I don't bother to check with a finger-stick unless I have a reason to suspect my G4.
Am I taking a risk? Yes. Is it an acceptable risk? That's for each individual to decide. I judge it to be quite acceptable. There are just too many times, routinely, that need a correction, but I'm not in a good situation to pull out the meter and take a finger-stick. However, it is easy and discrete to give myself a little juice, based on the CGM reading.
Why am I willing to take this risk?
Over the 4 months I've had the G4, I've found it to be very accurate
I have learned what circumstances in which to suspect its accuracy
I take mitigating steps to help prevent a problem from "overtreatment" (like a hypo from an inaccurate hyper reading)
I've been 100% successful so far... No hypos.
My main concern is overtreating a high; when my G4 is inaccurate on the high end, it usually reads lower than actual. In fact, I don't recall it ever reading too high, although I'm sure others have had that experience. It's not perfect tech, after all.
I can go into some of the details of any of those bullet points, if anyone's interested.
In the mean time, anyone else want to come out of the closet?
I have never taken insulin without a finger stick and I wouldn't ever do that, it's not worth the risk to myself and to other people. I do treat lows frequently before testing and then test after. I had a dexcom for about 2 months and it was very inaccurate, I never treated based on readings from it.
I used to do it a lot more than I do now. The only reason I stopped is I changed endos and she scolded me for taking insulin without doing a fingerstick first (My pump told on me :() I still regularly treat lows with it and I have few problems. :)
I have occasionally taken insulin based on the G4 alone. I also find it to be very accurate, except in ceertain circumstances - for which I always check with my meter. I have had highs that Dexcom reported that were in fact higher than the meter (dexcom: 170, meter: 131). Mostly, it seems like it fails to "recover" from an extreme - high or low - very quickly, so there's some risk on that end.
I get headaches when I'm high, so if the G4 says a high number and I have no headache, I test. I have to test before correcting on the low end, however, because I am partially hypo-unaware. If I don't feel it and is says low, it might be wrong - and often enough is.
I do with my Medtronic too. I am usually pretty confident in the numbers and am also pretty conservative with my food habits. I have pretty much the same "bullet points" Dave has. A lot of my more adventurous behavior is in the evening and if I "whiff" and end up low, I just treat it...
I may get bit one day, but I doubt it. One of the mitigating steps I take when treating a high based on the G4 is to set the low alert at 100, so I can catch the BG on the way down and keep an eye on it. Depending on how it's arriving (down arrow, plane falling out of the sky, horizontal arrow, plane coming in for a nice, smooth, gentle touchdown), I'll counter-correct with some skittles.
Also, I don't rely on the G4 when I know, from experience, it's not as reliable. First 2-3 days after a sensor change; asking for calibration in addition to screaming I'm hyper; I'm sick; and a half dozen or so other conditions.
I always treat serious G4 hypos immediately (<60) without a BG check, then check after eating something.
It's your body, your life... don't let an endo intimidate you out of treating yourself in a way you find totally reasonable and acceptable.
As others here show, opinions on this range widely. That is due, certainly in part, to the fact that we are all different in the way diabetes functions for each of us. Meee's unfortunate experience with the G4, vs. mine and others, is a great example. For some reason the enzymes on the G4 sensor wire don't play nice with Meee (which is a major bummer).
Normally I’m with you on not letting endo’s intimidate you…but in this case she was willing to write me a prescription for the strips and fight my insurance to get them…so I’ll stick myself a few more times a day
Dave - Good topic to discuss. I've used a CGM for four years now. I've found that you can make treatment decisions based on the CGM alone but only under certain circumstances. I don't ever trust the Dex alone in the first 24 hours of the sensor. I have made some bad decisions and learned from mistakes.
If my Dex has been correlating well with my finger sticks, then I'm more apt to treat with the Dex alone. Where it most often comes into play is when the Dex wakes me up at night and the alarm makes sense based on recent history/trends. Most often I'm treating a 150 with a small dose of insulin at say 5:00 a.m. and plan on getting up at 7:00 or 8:00 a.m. It's most tempting to do this since I don't want to wake up enough to fingerstick. I just want to get back to sleep, I'm only making a small treatment, and recent history supports my decision.
If I'm awake, I'll usually fingerstick to confirm because it's so easy to do. If the Dex number requires a large food or insulin correction, I'll fingestick just to be safe.
That being said, I hesitate to recommend this to new CGM users because it's easy to get into trouble. It helps to get a lot of fingerstick/CGM comparison experience before attempting to go with the CGM alone.
I guess its all about the balance of art and science in managing blood glucose. Sometimes your gut sense just overules the arithmetic. More often than not, however, I like to rely on the science and numbers.
Great post, Terry. You touched on most of the things that go into my "decision criteria" for treating based on CGM data alone.
Over the months, I simply found that during the "sweet spot" -- days 3 through 10-20 -- I have superb accuracy.
So one of my gating factors is if the sensor is 3-10 days old. Outside of that range, I don't trust it exclusively to make treatment decisions.
Of course, I fingerstick 4-8x a day as well, so I have plenty of "spot-check" validation to tell if something whack or not.
I guess the point of this topic was to break the taboo, and talk about it. I was pretty sure others were treating sometimes from their CGM alone, not just me. Learning from each other (the point here) so we are all safer and achieving better control is the ultimate goal.
There are just times when I'm not in a position to do a fingerstick, but can easily pump a little juice to get things back in line. For example (I know I'll get chastised for this :-)) I've given myself corrections many times while driving my commute -- close to an hour -- while obviously I couldn't do a glucose test. Never had a bad outcome.
HOWEVER! Your point is well taken for noobies... New users should get plenty of experience under their belts, and share and learn from the community, before going to these more "advanced" treatment options.
Well, I started this topic over a year and a half ago, and a lot has happened since then.
I’ve become much more experienced managing my diabetes with a pump and CGM.
Dexcom updated the firmware in the receiver and substantially improved the accuracy, and duration of accuracy, for me at least.
With the new firmware, G4 sensors in my body are accurate immediately, have excellent accuracy during 12-hour calibrated operation for the first 24-48 hours, after that accuracy routinely extends 24 hours or more without calibration.
I always get at least 14 good days out of a sensor with the new firmware, hit and miss they’ll go another week. So I just change them on a 14 day period as routine.
I’ve learned a lot about sensor placement and location, in particular how this impacts readings. Putting the sensor in a good location makes a huge difference in how closely the CGM reading match capillary blood from the fingertips.
So, to update this discussion, I’m treating on the basis of my Dexcom alone all that much more. To be frank, it’s my primary means of BG measurement. As I’ve said in many posts since the firmware update, it’s become scary accurate – rarely is it ever more than 5 mg/dl off my glucometer when I calibrate. I’m not exaggerating – it has been this way all the time since I updated the firmware last fall, with a small handful of exceptions (and those were when my BG was moving).
I swear I wasn’t the development team Guinea Pig, nor was I part of the Artificial Pancreas work that led to the new firmware. I’m just very lucky that my own boy chemistry seems to be made for the G4.
In any case, it’s my primary tool these days for making treatment decisions. I only fingerstick 1-3 times a day now. It just became utterly redundant to do any more.
I sometimes use my Enlite to take insulin, but then again I do that when it has been so accurate that it is between zero and 3 points off of a meter reading, which can happen for days on end. Another Enlite sensor may be unable to keep it’s ISIG’s up, and that makes it worthless. After a couple of days I call MM when that happens and they send out a replacement sensor.
I do find that most of the time the G4 is as accurate as you, and have treated based on it alone as well. The exception is when I have reason to disbelieve the CGM, in which case i test and see what the meter says.
Like everything else, it’s a balancing act.
