Hi, all. I am struggling with how to deal with this. I walk very fast, high heart rate, for 4-5 miles most mornings. I have been thinking I was getting post-exercise highs and then dealing with that at breakfast as best I can. I am up at 4am, have coffee and feed glucose tab if needed about 20 minutes before heading out. I also eat GTs as needed while walking, especially when arrow goes to down, not straight down. So, I have finger stuck before exercise and all is fine, but the minute I get home, level arrow, I finger stick and find my g6 reading 40 points BELOW actual. Then it proceeds over the next hour or so to get caught up to actual, but by then my day has a crappy start. I am on Tresiba and Humalog, just fyi. This is consistent behavior. I even put a Libre 3 on same arm (Libre is usually perfect for me, except overnight, but I do not prefer that system - it is terrible overnight for compression lows). Anyway, Libre can help keep me from excessive feeding , but obviously cannot wear both. And I am only talking an error of 2-4 grams of carbs that can mess up my day. I may just need 1 or 2 GTs before walk and not attend to. Anyway, can anyone help with this? Testing BG manually in the walk is not going to happen. I exercise in the dark with streetlights and cannot fathom v]carrying more. G6 is definitely 40 points off at completion and then slowly rights itself. In the past I have taken them off and called for replacement, but now know it gets back to its normal. Please advise is you can. Cold weather could also be a possibility, but I am in South Carolina and taliking 48 degrees. Still I believe it didn;t do this in warmer weather and I am dressed appropriately. Thanks for any anecdotes, science, opinions! Happy weekend!
Is there jitter (jumpy up/down dots not in a smooth line) in the graph? I’m starting to think that when the sensor algorithm detects inconsistent readings so it is not confident of accuracy, it reports numbers closer to the lower end of its error bars for safety. That is, if they think the BG is somewhere between 70 and 140 but they really don’t know which, they’ll report 70 to be safe. That way their error may lead you to treat and get high BG, but that’s not an immediate hazard whereas if they erroneously guide you to become hypo that could lead to a car crash or passing out or something.
Anyway, if this was a repeating pattern happening to me, I’d take less glucose in response to the CGM’s prompts during the exercise, splitting the difference between what they say and what I guess is actually true. Eric made a rig so that he can do fingersticks while running hard, as a way to avoid CGM issues during competition or training, so that could be an alternative if you find the errors and excursions unacceptable.
@bkh Thanks for that insight. Alas, the g6 has solid, non-jittery lines as if it is confident. Starts dropping within a mile, then later will have the down arrows. But wow! I don’t know why I didn’t think to even split the difference. That is a wonderful idea. Also, I have lately decided if I am a mile from home, I won’t do anything unless it is lower than 80 and going down. I think my GTs are seeming to take longer to impact my bg, as well. And I also admit, I get my rx’s for 90 days at a time and I have struggled with the accuracy for many months now where I have to calibrate much more often throughout the 10 days and feel the calibration (done with perfect hygiene and other protocols) sends it into the next 24 hours being weird, only to do that 4 or more times during its life. And I only calibrate when it is way off from the chart dexcom has, usually 25 or 30 points and at a time well past meals and activity. I honestly believe there is something different in g6s since last year and found notes I have made to that same effect from a bit over a year ago. I never used to have to calibrate - just would check with finger stick (Contour Next One) and find it working well within range. Wonder if I might need to try g7 again? I had some early ones that were not great, for me anyway, but they might work if I give it a try. Just love the way g6 app and clarity work and look. And I think you can calibrate g7? Just some thoughts! Thanks for a straightforward suggestion. I guess I missed the forest for the trees! I have had a pitiful month not understanding what was happening, though I study my patterns every morning for 30 minutes at least to determine amount of Tresiba and reflect on my I/Cs and correction factors. Just told myself it was post exercise high, then getting shocked at 40, 42 and 44 points below actual and seeing that breakfast bolus tried hard, but didn;t have any correction in it because cgm takes a few hours to right itself and then I was rising high by lunch. T1D is such a puzzle and a domino game! Tough to tell cause/effect from everyday body and life variations and then try to restrain from too much correction with glucose or insulin, and to get off the rollercoaster. I digress - thanks for the help, as always bkh! Take care!
Hi @Quadgirl
I am not sure if this is a factor, but how well are you hydrating? If you are dehydrated it can affect the Dex readings.
The G6 smooths the graph so jitter can’t be seen.
It’s with the G7 that I’ve gotten the vague impression that it estimates low when there’s uncertainty in the readings. I’ve almost never calibrated, and don’t worry about it because it generally works out ok even if it’s not right.
@Eric Thanks Eric. After the fact I knew I should have said I am one of the best hydrators on the plane. Haha, but years ago I just planned my water and amounts for exercise and glad to have the old habit with T1D. Thanks for thinking on it, Eric!
@bkh Thanks for that info. I think I am going to ask for g7. New sensor came on mid-day yesterday and within a few hours was within a few points of finger stick. By evening before bed, unfortunately, it was reading 81 and I was 60 which is lower than I prefer. I calibrated even though not within Dexcom’s limits because I wanted to feel safe in sleep. I will check again today at the 24 hour mark and hope it is accurate. Seems good now though, but I need to try the latest g7s, I think. Thanks a lot!
When you try it, please share your opinion and if you think it is better. Thanks!