Qualy #26 - What is Peter looking to achieve and monitor with his blood glucose monitor？
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Summary
What exactly are you looking to achieve and monitor with your blood glucose monitor? What are you hoping to achieve with your continuous glucose monitor (CGM)? In this episode of The Qualies, Dr. Peter Tmd talks about his own personal journey with his own blood glucose monitoring device, the Dex Dexa G6, and how it s changed his life.
Transcript
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welcome to the qualies a subscriber exclusive podcast qualies is just a shorthand slang for
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a qualification round which is something you do prior to the race just a little bit quicker
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qualies podcast features episodes that are short and we're hoping for less than 10 minutes each
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which highlight the best questions topics tactics etc discussed on previous episodes of the drive
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we recognize many of you as new listeners to the podcast may not have the time to go back and
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listen to every episode and those of you who have already listened may have forgotten so the new
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episodes of the qualies are going to be released tuesday through friday and they're going to be
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published exclusively on our private subscriber only podcast feed now occasionally we're going
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to release quali episodes in the main feed which is what you're about to hear now if you enjoy these
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episodes and if you're interested in hearing more as well as receiving all of the other subscriber
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exclusive content which is growing by the month you can visit us at peter tmd.com forward slash
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subscribe so without further delay i hope you enjoy today's quali what exactly are you looking to
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achieve and monitor with your blood glucose monitor your cgm your g6 which you another product you
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probably you love i love the g6 and i'll talk about it all day long without you know receiving
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advertising dollars to talk about it you know it's funny the g6 along with the aura ring which i've
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talked a lot about are these and i've worn every wearable that there is but they're the only two
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that seems sticky enough that i can't stop wearing them like if i like a month ago i went to charge my
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aura ring and i forgot to put it back on my finger when i went to bed so i slept without it and i woke up
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the next morning and realized i didn't have it i didn't have the data like it made any goddamn
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difference in my life i was so pissed the horror i was like god how could you forget to put your ring on
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last night there's probably a whole separate issue with with that but and the same thing with like
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the continuous glucose monitor i just it's hard for me to imagine i used to not know my glucose in
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real time so there are a couple things from it the first is it's a great way for me to control my
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behavior and i know it's tempting to want to believe that i'm somehow impervious to the forces of bad
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food but the reality of it is i am not there was a day i think when i you know had a remarkable
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resilience and willpower and i could do anything eat this don't eat that exercise like this exercise
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i could i was a robot for so much of my life until three years ago and something just happened in 2015
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and i just fell off the rails and i've never got back on i simply do not possess the intestinal
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fortitude to be a robot anymore and i could speculate on several of the reasons for that
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which i don't want to get into but the long and short of it is here i am i am in an environment
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where like you know yesterday i was on a plane and they were handing out shit cookies and bullshit
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i really wanted a cookie i think the only reason i didn't eat that cookie that was bigger than my head
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is because i knew i'd have to look at my cgm data after so there is no more powerful behavioral tool
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for me than my cgm because in the end i'm kind of a competitive person internally much more competitive
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internally than externally by the way and i just can't stand to see spikes of glucose it just drives
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me nuts and so which is not to say i don't go off the rail sometimes i absolutely do we were in
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but fenway park the other day and i had fries now luckily i'd fasted all day and worked out so i
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didn't actually experience a spike of glucose from the fries so i got to have the fries without the
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badness but i was sort of ready for it i was kind of bracing myself like oh you might you might get a
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little testy seeing this thing but that actually gets to the second point which is it has allowed me
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to very eloquently calibrate how to tether activity levels nutrient deprivation the consumption of treats
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and minimize the damage i don't know that i could drive a race car very well without seeing my rpm
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tack like if you plugged my ears so that i couldn't actually hear the rev of the engine and you took
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away my rpm tack and said drive could i still drive the car yes could i drive it half as well as i can
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drive it when i know exactly where i'm shifting at every moment where i need to shift no there's simply
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no way like we just we're feedback machines we need feedback so i'm a huge cgm advocate and really
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looking forward to what the next few years will bring when these things can become a lot more
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affordable and a lot more accessible and the question is can that be done without them remaining
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as medical devices so the one i wear now is the dexcom g6 is a medical device it's an fda approved
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device and it gives you a number that is in this case incredibly accurate it's probably plus or minus
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two or three percent specifically for the purpose of someone with diabetes being able to dose their
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insulin the fda will very likely not allow such a device into a consumer market because the concern
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would be that such a device could be used outside of a prescriptive relationship with a physician to dose
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insulin so therein lies a whole bunch of issues that would basically the way it would happen today
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is the fda would basically have to neuter the device such that the information couldn't be used for
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treatment purposes which means they either take away the real-time nature of it which is what makes it
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so valuable or give you a bunch of ranges and dilute the accuracy those are basically the two levers with
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which you could neuter one of these devices deliberately which sounds crazy right like it's like a
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backwards step okay i know you have a zippo lighter we're gonna start using sticks instead
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we're gonna rub them together you know so but all that said you know hopefully you know in an ideal
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world the medical device becomes cheap enough that if you want that level of precision fidelity
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and real-time feedback you'll just you know look doctors write prescriptions for way crazier things
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than cgms right i mean you got docs out there writing prescriptions for pain meds all day long
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and every hormone under the sun i don't think it's a big stretch to say doc i need a cgm and i think you
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might have mentioned this too in terms of what you are looking to achieve and monitor with your blood
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glucose you might have said that it's a proxy for your insulin and maybe you could explain why there
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isn't a continuous insulin monitor alongside your glucose monitor because that would be a
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that would be cool if it actually exists yeah and i looked into this a lot in 2011 and 2012 i even met
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with the engineer he's actually i don't know if he's still there but i don't remember his name now
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unfortunately but he was he might have been an emeritus professor of engineering at ucsd but he was
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actually the first guy to figure out actually how to do these real-time glucose monitors uh the what
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are called a point of care device and actually took him out to lunch one day to pick his brain on well
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why don't we just do this for insulin and he was like would that be interesting and it was just
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funny to talk to him because he's an engineer like why would he know that insulin would be as
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interesting as glucose or more interesting and and so we actually dug into this a lot and basically the
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the short of it is if you can't measure the assay using an antibody or enzymatic reaction that very
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quickly without any washing yields an answer you can't do it at a point of care device and insulin is
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pretty hard to measure so it was initially measured using something called a radioimmune assay i believe
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today they're usually done with something called elizas which are these enzyme link you know i won't
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rattle off what eliza stands for but it's it's a it's a chemical reaction where you have to you know
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put put an enzyme on something rinse it off put another one on rinse it off etc so in other words it
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can't be done in a moment so absent that i don't really see any direct way to measure insulin in real
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time now i've had discussions with some companies who are interested in using cgm data to impute
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changes in insulin and i think that could be done but i think it's a lot harder than people realize
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and you would need a lot of data to do it meaning you'd have you wouldn't just be able to do it off
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the cgm you'd have to do the cgm coupled with a lot of blood draws where you actually could you know
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basically build a regression curve off insulin and glucose to predict for future insulin therein may
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lie an answer down the line so absent that a good proxy for having a low level of insulin is going to
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be a low level of glucose and a low level of glucose variability and the cgm spits out those
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reports so you go you know you go into in low glucose variability one might yeah i don't know if
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people can see this but i'm going to infer that the the a1c might be telling you that although i
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don't the a1c is not telling you anything about the variability but i don't know let's talk about
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a1c in a moment but you can see that i can spit out at any point in time a 90 day 30 day 14 day or
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seven day report and that report gives me average glucose and glucose standard deviation that's the
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variability so why is that relevant well you could have an average glucose of 85 95 whatever with the
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standard deviation of 10 which is very low variability or you could have the same glucose
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level with a standard deviation of 30 and those are very different insulin profiles so you want to
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keep you want you want to keep that balance closer i've largely discounted hemoglobin a1c in an absolute
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sense as a meaningful number i think it's it's directionally tolerable but mostly shit and i know that
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because now i've used cgm in so many patients with calibration and compared it to a1c and you realize
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that the a1c is really at the mercy of its most important assumption which is a red blood cell lives
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for 90 to 120 days anything that takes it outside of that range leads to an over or underestimation of
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the a1c and therefore an over or underestimation of the average glucose and you can with a1c theoretically
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you can say i have an a1c of 5.4 and you can impute what your average glucose levels were
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theoretically yeah so the way the a1c works is you measure the a1c and you impute the average glucose
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the way the cgm works is you measure the average glucose which is actually all that matters but you
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can impute the a1c my a1c runs very high because i have this condition called beta thalassemia trait so
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i have a bunch of these little i think i talked about this in the podcast on one of the shit for blood
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i have yeah they used to call it yeah mattie used to call me shite for blood always in a scottish
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accent you got shite for blood so my little shite blood cells live a long long long time
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they i mean i have no idea but it's clearly longer than 120 days so my a1c is very high the lowest a1c
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i've ever seen in myself is 5.6 and the highest is 6.0 so i'm basically just on a1c i'm a pre-diabetic
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pretty much all the time on cgm when you take a highly calibrated rigorous you know look my average
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blood glucose imputes that i would have an a1c between 4.5 and 5 that's sort of the range that
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i would live in so that's a material difference and again i've seen that difference in both
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directions with patients using cgm so my hope is that in 10 years maybe that's ambitious i would hope
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that the hemoglobin a1c can't even be ordered on a lab and everyone just has a cgm you know and it's
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like a trivial little you know thing that you know even if you're getting a life insurance exam you just
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wear the cgm for two months and the data comes from that as opposed to actually measuring this
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nonsensical number i hope you enjoyed today's quali now sit tight for that legal disclaimer this podcast
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is for general informational purposes only and does not constitute the practice of medicine
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nursing or other professional health care services including the giving of medical advice
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and note no doctor patient relationship is formed the use of this information and the materials linked
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for professional medical advice diagnoses or treatment users should not disregard or delay in
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obtaining medical advice for any medical condition they have and should seek the assistance of their
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health care professionals for any such conditions lastly and perhaps most importantly i take conflicts
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of interest very seriously for all of my disclosures the companies i invest in and or advise please visit