My meter said 35. I checked a different meter, and it said 31. Rechecked first meter, and it said 34.
I feel fine. Dexcom is saying I am low.
Another meter check, and it again said 35.
?
Really feel fine still.
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Nope; Iād probably be nearly unconscious at that BG. Personally, feelings aside, Iād trust the (multiple) meters, but I live alone and canāt afford to make an error of undertreating a low.
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I still donāt know what was going on. I ate a few crackers, just to be on the safe side. Nothing very sweet. And about 30 minutes later, my BG was 134. So I still donāt know if I was actually low.
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Definitely weird! 
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I would trust multiple meters. Are you still hypo alert?
The lowest Liam ever got was 28 and i was scared senselessā¦he was very drowsy and I was about to give Baqsimi when he started coming to again (he had already had fast carbs earlier). Heās been in the 30s a few times over the yearsā¦equally as scary.
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I generally know before my Dexcom does!
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When I see the Endo he seems amazed Iām still hypo aware. Then again I think heās amazed Iām still aliveā¦lol
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Youāre so lucky youāre hypo awareā¦. my awareness has been gone for a long time!! Went to the clubs 25ish years ago with my boyfriend (now my husband), came out of a club, and my meter said 29.
I didnāt feel it - hubs said I was falling asleep trying to cross the street to our car. I got orange juice, and everything worked out. But I saw that meter read 29, and thatās the lowest Iāve ever been conscious enough to remember!
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Itās so weird ā I totally understand feeling fiiiine in the 40s, but whacked out shaky low in the low 70s. I donāt know whatās going on these days.
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A few crackers could send my bg up by 100mg/dL in around 20 minutes; 20g of crackers (3 crackers possibly) on an empty stomach but, like you I suspect, Iāve never been near 30mg/dL and not known about it 5 minutes before.
I see only two possibilities:
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Low interstitial blood glucose in the fingers (Iām assuming literal fingersticks here) caused by extreme conditions, maybe cold or rapid finger exercise; Iām BSing here but it does seem possible.
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A chemical interference with the BG meter test strips (Iām discounting the Dexcom because in my experience it can say otherwise hilarious things at quite reasonable BG). Thereās a long list of things that can mess up test strips and, for that matter, CGMs; Linus Paulingās favourite (ascorbic acid) comes first.
Both effects are in the fingers (unless you were testing somewhere else, toes?) So something localised lasting for less than 30 minutes. I donāt think the CGM reading is relevant; yeah, maybe it is somewhere different but the darned thing is so inaccurate below 100mg/dL.
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Thatās the feeling. Itās not like being drunk, or tired, or just plain worn out. Itās an inability to focus, yes, a slight unsteadiness like inebriation, but a feeling of being BG low.
I donāt think non-Ds understand it; most non-Ds seem not to be hypo-aware even though many, perhaps all, of them suffer from hypos now and then. It is not something we lose; it is something we develop and more and more.
Sometimes these days I feel Iām going low when by BG is, according to all the devices, around 90mg/dL. Thatās not because Iām accustomed to high BG; these days with modern tech my average BG (HbA1C, TIR etc) is much much lower than it ever was. Maybe Iām hyposensitive?
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The Brains and the Fingers blood supply and their glucose content can be at times far different because the Brain is supplied from arterial blood compared to the capillaries in your fingers where you get finger sticks from, itās possible this can vary by a lot depending on the situation. The body (finger capillaries) in my example could be (say) 1 mmol ~ 18 mg/dl while the Brianās blood sugar (from arterial supply) maybe (say) 5 mmol ~ 90 mg/dl. This is often why you will have extremely low blood sugars that you read from a finger stick but still be conscious and feeling ok. Itās not lying to you or in error, itās that the brain and capillaries are out of āsyncā, but if you stay low for long enough they will eventually reach āparityā. Bernstein had video on this as someone wrote in to him and asked him this question.
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Extraordinary claims require extraordinary evidence. I want to read three high quality references before I believe that statement.
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Itās not a scientific statement, itās just what Bernstein said and I can say from 50 years of type one at every stage of life it appears true in that at 1.8 mmol Iāve been quite conscious and Iāve also at 3.2 had to be revived by paramedics. It should be clear that CGM blood differs up to 15 minutes behind venous gas, so it shouldnāt be a stretch to think that the brain is behind or in front of the venous supply. Now, Iām unsure if this can cause significant differences that could explain that situation I wouldnt know, Iām not a Dr, but I certainly donāt think itās āextraordinaryā in any way, itās either true or itās not, but I would like to know why this happens, I guess when I heard Bernstein say it, it made sense but now you ask Iām very curious.
EDIT: Turns out Chatgpt agrees with Bernstein, hereās what Chatgpt said, but again like you said, you wouldnāt want to trust this information, verify it if itās important:
Great question ā youāre digging right into the physiology of brain glucose vs. peripheral glucose and why Dr. Richard Bernstein talks about this difference.
1. Blood glucose is not the same everywhere in the body, when you prick your finger, youāre measuring glucose in capillary blood from the periphery, the brain, however, gets glucose delivered through the cerebral circulation and across the bloodābrain barrier (BBB).
The concentration in finger blood, venous blood, and interstitial fluid (where CGMs measure) can differ, especially when glucose is changing quickly.
2. The bloodābrain barrier (BBB) acts like a buffer
Glucose crosses the BBB mainly via the GLUT1 transporter, which is saturable and maintains a fairly stable supply to neurons.
Because of this, brain interstitial glucose lags behind and smooths out rapid changes in blood glucose.
So if your meter shows a very fast drop to 1.8 mmol/L, your brain may still have ~3ā4 mmol/L in its interstitial space for a while.
This āreserveā is what can keep you conscious at readings that look dangerously low.
4. Other factors that explain the difference
Counter-regulatory hormones (adrenaline, cortisol, growth hormone, glucagon) affect symptoms, not just numbers.
Adaptation: people with tight control or recurrent hypos sometimes tolerate much lower glucose before losing consciousness ā the brain adapts to run on less glucose.
Alternative fuels: in prolonged low states, the brain can burn more ketones or lactate, temporarily sparing glucose.
So in short:
Finger-stick glucose ā brain glucose.
The BBB smooths and lags changes, so your brain can have more fuel than your meter suggests (keeping you conscious at scary-low numbers).
Once the gradient collapses, IV glucose is needed to push enough sugar into the brain to restore functi
Do you want me to sketch out a timeline/graph that shows finger glucose dropping fast, brain glucose lagging behind, and wh
ere consciousness fails? That would make this much clearer visually.
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@genix While I appreciate the capabilities of ChatGPT and other AI systems and have found those of Google and others usually relatively correct, I know from experience with the few Iāve tried that their responses can be skewed by how a question or request is phrased. In addition, there have been significant errors reported based on sources trusted to ātrainā an AI system which also skews the information concluded or provided by AI systems. My take: AI systems usually make for a decent, if not great, starting point but require review, confirmation, and verification by users, particularly those that didnāt design or havenāt developed a history with a particular AI and determined a level of trust for it.
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@eric has mentioned something like this before! I donāt know that it relates to arterial blood necessarilyā¦ but heād mentioned, āThe brain uses the GLUT3 glucose transport. Since GLUT3 is a high-affinity glucose transporter, only a small amount of glucose is needed to saturate it.ā More info and reference here: Fixing the Low to High Rollercoaster - #2 by Eric
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Coming late to this fascinating thread. As we all know, Dexcom can be completely whacky - especially in the first day after insertion. Iād say I have false āurgent lowā readings about 25% of the time with new Dexcom sensors.
But this is a different issue, and I appreciate all the hypotheses, both @jbowler and @genix
Genixā explanation seems plausible to me even if it doesnāt have a lot of scientific studies.
Another explanation, which is more worrisome for @eric, is that heās losing his ability to tell when heās going low.
Hope that doesnāt turn out to be the case.
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Well I donāt know what happened in this case, but Iāve been beating the Dexcom to the low all day today!
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I think itās 100% for me. It is certainly true that I have got low enough, maybe approaching 60mg/dL on a fingerstick, to trigger a Dexcom alert but, like @eric, I always knew before the CGM ever got there. Iāve had a few, not a lot but a significant few, of Dexcom false alerts. They happened in the morning mostly. They seem to happen when I am particularly insulin sensitive and go out and do stuff that would use the insulin sensitivity, I thinkā¦
My data is from memory and is apocryphal. I really wish my āphone would log my exercise level and that xDrip+ could read that and send it to NightScout but then Iād need NightScout to produce data in a format that was considerably more amenable to my own data processing abilities.
What @genix said is entirely consistent with what I said; the two statements are at fundamentally different levels in the process, though I should have said ālow capillary blood glucose in the fingersā. @genix provides an explanation based on the buffering of glucose in the brain. I donāt think the different transports are relevant to the explanation.
The buffer damps venous variations in BG, so a spike (down) in BG can occur in the core blood system (veins and arteries) and be reflected in the capillaries without ever being seen behind the blood brain barrier. Thatās kinda useful 
@eric didnāt say if his BG had descended ārapidlyā and the limited amount of research I could find didnāt give me a half-life for the damping; if itās 1/2 hour 15 minute variations will disappear etc [rule of thumb.]
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The Chatgpt thing was to show It agrees with Bernstein, after all itās him that made this claim first, and I find I agree with Bernstein, Medical school physiology and chatgpt in their instance and all the power to you especially on the Chatgpt front, and again Iām not going to find first year medical texts to show interstitial fluid, venous blood, capillary blood, and both arterial blood and arterial blood gasses along with the blood brain barrier (barrier being the key word) arenāt all separated systems. I will guarantee though they are all separated and can have vastly differing glucose values especially the brain which has mechanisms to protect itself from sudden changes in many things including glucose.