87 replies
1d2h
I dove into CGMs a little bit about a year ago, mostly just for fun. Yes, I paid money to some online prescription mill for CGMs (Abbott Freestyle Libre 3, IIRC), and then put one in my arm (the applicator is a short syringe section that has the monitor tube threaded into it, so the tube stays in your arm and your skin under the monitor remains broken) for a couple weeks. Just to see how various foods would affect my blood glucose, to see whether the “facts” I’m telling my kids about the glycemic index of various foods actually has the expected impact on a measurable result. You know, as you do. For fun.
(It actually was fun, and I’ll do it again when the data ecosystem improves.)
Aside from the fun, how did it go? Find anything surprising or insightful in the process?
It sounds like an experiment I’d like to do for the purpose of optimizing my daily habits and establishing a better mental model for how my eating habits impact me throughout the day. But I really dislike needles.
If the needle in the CGM bothers you, don't let it. It's a quick, painless jab with a tiny needle at the beginning and then the needle comes out. The part that stays in your body is just a flexible filament made of plastic.
I did this experiment as well, and the main thing it did was completely stop me from snacking. My habits got better because I could see how my BG could never return to baseline if I allowed myself to snack between meals.
Other than that, it was also interesting to see certain things would badly spike my BG and other things wouldn't, and they weren't always what you'd expect. A lot of "keto" and "diabetic-friendly" products are terrible for most people's BG and were for mine. I found that some things, like black tea, actually made my BG drop as well.
Overall it's worth doing at least once.
My understanding is that for healthy individuals, spiking blood glucose levels is not a problem. Did you get in to any of the research on that? Glucose is a problem for diabetics because they can’t regulate it, but healthy people can. At least this is loosely what I have heard, somewhat third hand. Any information is appreciated.
Not a doctor, but from what I have seen, there is a healthy amount of spiking from eating normal foods, but our modern diets are so sugar and carb heavy that the glucose spikes are way outside the range that our bodies evolved to handle. Hunter gatherers would maybe eat some berries here (much smaller and less sweet than modern berries) and there. The modern human eating pizza, tons of bread, ice cream, soda, etc. creates such massive glucose spikes that they are unhealthy and unsustainable for the pancreas to handle for 60+ years.
Again, not a doctor and not sure if this is accurate, but this is my very limited understanding
> Hunter gatherers would maybe eat some berries here (much smaller and less sweet than modern berries) and there.
Archaic humans had access to plenty of wild fruit that were high in sugar and tubers that were high in complex carbs. They even had access to concentrated forms of sugar like sugarcane and honey.
They obviously didn't have refined sugars in everything they eat like we do but that they had access to limited sugar in the form of berries is a persistent myth. They would have been exposed to large glucose spikes regularly whenever they came upon a new tree that was in season while migrating.
Not to mention humans 150 years ago who ate plenty of bread and still didn't have the problems we have with obesity and diabetes. Or even 50 years ago...
That could also be because a fair amount of the bread in supermarkets today is closer to confectionary than homemade sourdough.
light bread starts turning into sugar almost instantly in the mouth and stomach. It's only one step removed and saliva can break it down quickly because it has amylase. Sour dough and whole wheat/grain breads tend to break down a bit slower. You can freeze bread overnight and make it a bit more "resistant" to breaking down quickly and I pretty much do this with all my breads along with toasting them a bit for sandwiches. Pasta can similarly have its glycemic index lowered by first making it "cold"
Do you mean that they need to be cold when they are consumed, or is it the process of freezing itself that does something, even if it's later reheated?
The process of cooling down converts starches in rice, pasta, potatoes etc... to a more resistant forms that your body cannot process easily.
Does chilling also work to convert bread starches into resistant ones, or does it only work for rice and potatoes?
GP mentioned bread specifically. I looked up some studies, and they are in agreement: https://pubmed.ncbi.nlm.nih.gov/17426743/
They don’t need to be cold when consumed.
That’s not really a fair statement. Many problem who would die of diabetes today would have died of something else 200 years ago long before the diabetes got them. Non-juvenile diabetes is a slow killer, it’s really hard for it to kill you before the age of reproduction.
A diagnosis today that is imminently manageable like asthma was far more readily in a world without antibiotics, steroids, or even medical oxygen.
Even something like a CPAP that many of us take for granted has only been readily available for 30 years or so.
Plus, diabetes is much like AIDS in that it’s more of a systemic thing than acute. It doesn’t really have symptoms that kill you. It just slowly weakens your body until your heart gives in, or you have a serious infection, or something like that. No one dies “of” diabetes, they die with it.
We live 2x-3x longer than we used to. We should take the best possible care of our bodies.
Only as a statistical average. Hunter gatherers who survived past age 5 had a good chance of living into their 60s and 70s.
There would be skeletal evidence of that. The oldest remains of early humans points to 35-40 year olds with high child mortality rates per https://www.hurriyetdailynews.com/people-lived-up-to-40-year...
They also moved around more than most people do today. Most of us are stuck sitting pretty much all day in front of a computer.
fruit and berries do have sugars but in their wild state they tend to have much less than their modern equivalents bred to be sweeter and tastier. Even then they still typically are 75-95% water and often have some fiber, antioxidants, and vitamins which all can help with inflammation unlike snickers bars.
It's not really that the pancreas itself can't handle it (though this may be true also). What happens is that having high blood glucose, even if it's not continuously high, is just bad for you by virtue of the high concentration of glucose in your blood. Having high blood glucose leads to the creation of "Advanced Glycation Endproducts" (AGEs) which bind to certain receptors (RAGEs). The AGE-RAGE interaction is linked to downstream diabetes side effects like atherosclerosis.
There's also research that indicates that cancer thrives in high-glucose environment, and that starving cancers of glucose reduces their size over time.
I have better life expectancy then them.
The longevity people think that blood glucose levels are an important predictor for rate of (biological) aging. See e.g. https://www.lifespan.io/topic/blood-glucose-is-a-biomarker-o...
Well, they're not just people. They are longevity scientists.
longevity scientists are just people
I'm not the OP, but I had a CGM several times through Levels. I can tell you that the major spikes (glucose over 200 after sitting between 80-90) really made me feel like shit. The 2 times I can remember it getting that high were when I had too much sushi, and a huge bowl with white rice from Chipotle. Brown rice never seemed to spike me nearly as bad, especially if paired with something high in fiber like black/brown beans. From a long term health perspective, I have no idea if it's a problem or not. I didn't like how bigger spikes felt, so there's probably something to it being bad for you long term. Obviously the more often you spike as a "healthy" person, the less sensitive your body is to insulin. Staying even on my glucose levels is always where I felt the best.
straight rice and bread break down into sugars -very- quickly in the stomach, that's why mixing them with stuff like you mentioned (heavy in fat and/or protein) can really dampen the spikes in my own observations. Those are just anectdotal though and what works for me doesn't work for everyone. I do like to eat a salad first with some good fibrous veggies though OR something like eat some of a chicken/fish entrée or steak if I'm having that as part of a meal.
My A1c is right on the edge of prediabetes, so I wasn't as concerned about the spikes as I was about my baseline, how long spikes last, etc.
With Type 1 Diabetes, your pancreas is no longer producing insulin, with Type 2, it's typically that it's not producing enough insulin. My child is healthy, but his pancreas stopped producing insulin years ago. He lives with T1D.
Where do you put the needle thing? Does it get in the way of everyday things?
No it never gets in the way. I would not recommend doing it unless you are a diabetic, the results are not that interesting. It took me two years to get used to smacking that needle into the upper arm/stomach/leg, spending up to 20 min -40 min getting over the fear was not a fun time.
I feel for anyone who has both diabetes and a fear of needles.
Having said that, it's no bug deal for 90% of people.
T1D here, needles are nothing compared to everything else an insulin dependent diabetic deals with. I guess only maybe 1 out of less than 100 shots hurt that much. It only happens when a nerve bundle is hit, then it smarts but it is still less bad than either high, or low blood sugar as well as how insane most every part of American 'health care' is. The main tricks for comfort are go with 29 gauge not the narrower more fragile types with the higher number gauges. The narrower ones have more fragile needle points and they can get damaged by bending during the insertion into the bottle. The other trick is to make sure the alcohol is dry before you take the shot.
Typically it is on the back of the upper arm where it is covered by a short sleeve shirt. Generally it does not get in the way.
I also use a piece of kinesiology tape to make sure my CGM does not fall off.
I keep mine on the front of my upper arm, where I automatically notice and protect it. The back of my arm usually means it's off in a few hours.
The needle stick a flexible tube in a few mm, then the needle pulls out.
Think of it as a 5mm thick patch and ignore the tiny tube sucking your blood.
The sensor typically goes on the back of your upper arm (your tricep). You can accidentally bump into things with it, but it was infrequent enough that it didn’t bother me.
The needle is only used in the application of the sensor. It’s spring-loaded and retracts after the sensor is attached. I hate needles, but I found that the tape on the sensor provided enough stimuli to overwhelm my brain and not really feel the needle when it went in.
Absolutely, there are a lot of companies trying to cash in on this new-ish market, and they'll do anything to their products to get the net carbs down to 0-2g "per serving" -- scare quotes around that because this is a particular annoyance of food labeling in the States: food labels declare the amount of various nutrients per "serving", but 1) they get to choose the serving size [0] and 2) they get to round numbers, so if they just pick the serving size such that it's 1.499g of carbs per serving, they get to put that it's "1g", and so on.
It makes it impossible to compare food labels between different items even among the same manufacturer (and even the same SKU but different/later packaging, because they don't have to issue a new SKU when they change the food label). If instead they were required to show amounts in g per kg (or ml per l for liquids, or whatever), they could be compared more easily.
[0] The FDA provides "Reference Amounts Customarily Consumed" and asks manufacturers to refer to them when deciding their serving sizes, but (from [1]):
so really they can pick almost anything they like
unless the food is medicinal in some way, I guess?
[1] https://www.fda.gov/media/102587/download
That's good to know. I think my aversion to needles is so strong that it stopped me from going beyond basic research. Bad on me.
But this does sounds like an interesting thing to try, if only to get a better idea of how my body works.
I've been tracking walking vs. resting heart rate, HRV, blood oxygen levels, and sleep for a few years using the Apple Watch, and while I know these measurements are imperfect, they've helped me better understand the impact of certain choices.
There's something that seems really beneficial about feeding my brain data about myself as a way to do the healthier things I've always wanted to want to do. The more data I have, the easier it feels to implement positive habit changes in a way that doesn't involve sheer willpower. There's something very satisfying about seeing the very tangible changes on a graph over time that indicate better health, even when it doesn't feel like the changes have done anything noticeable yet.
If you want to know more about it you can just read about how diabetics treat different foods. Short version; high GI is fast high blood sugar, lots fat and sugar can results long period of with high blood sugars.
It is a CGM more or less what you would expect, insulin is the only hormone that lowers blood sugar, then you have all the stress hormones that raise it like adrenalin, growth hormone and cortisol plus glucagon for long time storage of sugars in the body. So measuring blood sugar with a CGM gives you a value between 2.9-13.5 mmol/liter that is supposed to give you picture of a rather complex system. A CGM also needs perfect access to your free flowing blood which in it self is a difficult task.
I'm more curious about the experience a non-diabetic person has. For one, the purpose of using the device is quite different, and not related to a life threatening situation. And because the focus isn't to manage this specific issue, the insights and potential utility seem like they'd be of an entirely different variety.
e.g. I know that the things I eat impact my blood sugar, but don't have the same kind of intimate awareness a diabetic person would have, nor would the changes in my levels have the same meaning/impact.
Put another way, and setting aside the issue of oversimplifying a complex system (so is measuring RHR, HRV, blood oxygen, etc.), the benefit of CGM for a diabetic person is obvious. The benefit of CGM for a curious person less so.
It is probably easier to find interesting things curious people with diabetes has done, sure you might want help to sort out the interesting bits.
Optimizing sugar in take for exercise might be an interesting thing todo as non diabetic. There is no tool to continuously measure ketons though which is the fun part. CGMs are so slow. I really see no use at the moment.
Main benefit is more data, only work is to accurately log meals and activity.
I thought CGMs measure the interstitial fluid?
I'm asking out of curiosity here: I've always heard that fat doesn't spike your glucose at all and protein only if you a considerable amount of it. So from what you said if you ate a fatty cheeseburger (plated like a steak and without the bread) that your blood sugar will spike? I'm currently doing a Mediterranean style diet during the week and slacking off a bit on the weekends friday evening through Sunday morning. I have done keto in the past though with the readings I've done on it saying that lots of fat, some protein, and just a little bit of carbs should basically keep any glucose spikes very low. I could only handle the keto for a couple months though.
I almost completely forgot about the monitor itself, and only paid attention to the numbers on my phone. It's that unobtrusive (at least the Libre 3 one that I used).
I let the needle (actually: annulus? see sibling comment) get into my head because I was curious and looked at it. It looks a lot scarier than it is, kind of like using contact lenses for the first time: before you've used them, you get into your own head about it, but once you've done it a couple times it's just rote and easy.
I had started the first one a day before I started a few weeks of (6-days-on, 1-day-off) keto. Keto guides will say that you should have <= 25g net carbs per day, but I specifically wanted to see how front-loading (having almost all the day's planned carbs in one meal) affected blood glucose, and also whether the number (25g) is accurate for my physiology. I found that my number was closer to 30g and that when I stayed under it, my blood glucose spikes had very short duration but when I went significantly over it, blood glucose stayed higher for longer.
edit: One more thing, I used this time to play around with various sugar substitutes and see how they affected my blood glucose. Allulose came out as the winner (if money is no object) based on not having any noticeable off-taste or aftertaste and on measuring gram-for-gram the same as sugar (well sort of, it's only like 80% as sweet as sugar, so you get the same mechanical effects of sugar if you weigh it gram-for-gram and your baked goods or whatever come out not quite as sweet, which is perfect for me. Creaming butter with liquid stevia extract or something just plain doesn't work.
what other sweeteners did you try? Can't get allulose in canada (unless you buy it from a shady importer) because Health Canada says there isn't enough data to say its safe, so its not approved sweetener.
Freestyle Libre 3 only has a plastic filament and the plastic applicator pushes it in without pain. Very different than metal lancets (stick test). I can't feel it at all when its in the back of my arm. If I were worried about sweating too much and it not sticking I would get one of the third party over-patches that create a lager adhesive area. I might do that in the Summer.
My girlfriend uses the Libre 3 and I was wondering how it worked with just that plastic filament. She doesn't feel it at all when I apply it. We found that if she washes the area with soap and then just relaxes her arm and lets it hang freely, I apply it to the back upper arm, it just stays on and doesn't get in the way.
I did it for fun about a year ago and found out I had T2 diabetes.
I was shocked but obviously glad I found out. I use them from time to time just to see how I’m doing and how different foods (and amounts of them) impact me.
I found I can control it through diet alone and exercising when there is a spike by using a GCM for the constant feedback.
They are very expensive here though (UK) and my doctor won’t prescribe me one because metformin is cheaper, so it’s not something I can use all the time.
I hate needles, this really isn’t like a needle though, it’s a small filament which sits just under your skin, you can’t feel it, I thought it hadn’t gone in until I saw the reading appear on my phone.
Some things I found out besides what foods and amounts give me big spikes are that I have a blood glucose spike in the morning just before I wake up, and that if I eat a small enough portion of white rice, ice cream, bread, whatever I can reduce the spike quickly by going for a walk. If I had a lot though, a walk isn’t going to help.
Before I got cancer, I had one through Levels, and it was informative. Dessert is much worse than I'd thought. Rice, too, including brown rice. I remember eating some biryani and a small bit of naan at an Indian restaurant and thinking that I'd been pretty healthy, only to see a spike of like 80.
Momentary high blood sugar is perfectly fine after eating carbohydrate-rich meals.
This was down voted, but it's all about the time scale. A major pathway of transporting energy from your food to your cells is via glucose in your blood and your cells then use or store it for later. Insulin production reduces the spike, but that response isn't instantaneous.
So on a second by second basis numbers that would be concerning across an hour are fine. Similarly your average over an hour post meal can be much higher than a healthy average across a day.
Yup. A1C, which is the main diagnostic measure, due to the way it’s measured is a roughly 90 day moving average with somewhat of a recency bias.
Like most things, it’s mostly about area under the curve, as long as the extremes aren’t too much so.
for sure, the length of the spike is just as important, it's like energy and it's an area under the curve type of phenomena
I saw an interview a while back between Tim Ferriss and someone who had tried CGM for fun/research. One thing he noticed was the huge impact a short walk after a meal brought down his blood sugar levels. Tim then mentioned he experienced the same thing and that there is a saying in China, something to the effect of, "take 100 steps after a meal, live 99 years." This also linked up with something I had looked up a few years ago when I noticed that I always saw families of Indian decent walking around neighborhoods, but never anyone else. I looked it up, and founds there is a word in Marathi of taking 100 steps after a meal. (https://en.wikipedia.org/wiki/Shatapawali)
It seems there has been this age old knowledge that taking a short walk after a meal is really good for you, which somehow got lost in some/many cultures. My parents would always say they had to sit after a meal to let their food digest... it never really made sense to me. My grandma, on the other hand, is 103 and gets pretty upset if people try to stop her from walking after a meal (or whenever she wants). We always just thought she liked walking, but maybe there is something else driving her, it seems to have worked out for her. It was very interesting to hear the CGM back up some of these practices that have likely been going on for hundreds or thousands of years.
I have been wanting to try one. This approval opens up the door. I think seeing something like this with my own eyes, with my own body, with actual numbers, would have a bunch bigger impact than some anecdotal stories from others and nice sayings which align.
It looks like there is some research being done in the area as well.
https://link.springer.com/article/10.1007/s40279-022-01649-4
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8912639/
Taking 100 steps after a meal is a common saying in India as well. The saying also advises sleep on ones left side for good health. Goes like this in Kannada - "Undu nooradi nadedu, edamaggulagi malagidare vaidyana bhandatavilla sarvajna"
Literally "if you walk a hundred steps after eating and sleep on you left, there won't be any doctor's shenanigans"
sleeping on your left side can help with gastrointestinal issues somewhat (like reflux) or after eating an acidic dinner.
That's fascinating -- you know how your body sometimes manifests a craving for a food when it "knows" that you're deficient in some nutrient that food will provide?
I get the same feeling (of my body directing me to take some action) but it's not after meals, for me it's after having more than one beer. After 2-3 beers I want to go walk around the neighborhood for half an hour (and it's a bummer when the neighborhood is not pedestrian-friendly).
Desserts can definitely send your levels quite high but I don't think I'd qualify some biryani and naan with a reading of 80 as unhealthy. You probably ate a healthy portion and left it at that. Is 80 not well within the normal range?
He probably means it spiked 80 from where it was (e.g. 100 to 180)
Which is still pretty normal, low for a full meal if anything, if not presiding with insulin.
Eat fiber first. Add more protein. Eat reheated rice (resistant starches). Isn't it interesting how much these little details matter?
healthy proteins and fats are good for you, both will slow down digestion time. I rarely eat only rice as the main course of a meal, and usually eat something either with it or before it, and it's almost always brown rice.
Is 80 high? That seems totally fine.
80, as an absolute reading, is on the low side of normal. Like, that’s what it might be first thing in the morning before you eat. Anything sub 50 starts to get dicey.
At least for me the readings that it shows are not accurate (when verified with old style finger pricking glucose monitoring machine). These CGMs are good for knowing the general variability of glucose level in your blood based on your diet exercise etc; I don’t trust the absolute numbers from CGM like Freestyle Libre - haven’t used any other one though yet.
It would be interesting to see whether a group of 20-100 people could manually calibrate their readings by fitting their CGM readings to their fingerprick glucose readers. I wonder what the accuracy would be after a very basic personal curve fit.
I do this with a lot of consumer measurement devices. Both for thermometers and scales (food, human, and cheap 0.1mg scales). As well as thermostats, like the kitchen oven. I also do it for my multimeters. I validate my volumetric measuring cups/spoons by weighing water in them but I don’t correct them, just return if they’re way off.
It’s okay if the reading is off as long as I can correct it the same way every time and get a pretty accurate result.
Calibrating my scales and thermometers would be nice. What procedure do you use for it? is it documented online anywhere?
I basically use an Excel sheet. Make a scatter plot of the "true" values on one axis, and the "measured (slightly wrong)" values on another axis. Then do best-fit to y=mx+b and manually adjust it according to that equation using my phone calculator in the future.
Some classically trained engineers may tell you the "true" value should always be plotted on the x-axis as it is often considered to be the more "independent" variable...but this is highly debatable, and you can skip some simple algebra later if you put the measured value on the x-axis. Then look at the shape of the scatter plot. Ideally it will be linear, so you ask Excel to do a linear curve fit (y=m*x+b). Write this on the scale, and now whenever you take a measurement on the scale, whip out your phone and do "measured_value * m + b". And that's your true value. If it's not a linear fit (quadratic, log, etc) ... that's interesting, and often it's likely "wrong", but also "it is what it is". Classically trained engineers will say you have to do a linear fit if that's what the theory says is appropriate, but for one-off home device calibration...do whatever works for you. Just as long as you don't overfit with some stupid 4, 5, 6, etc-term equation. Any reasonably simple equation with 2-3 terms is fine IMHO.
I use a set of heavy objects whose mass I know fairly precisely. They're not perfectly 10.000lbs, 20.000lbs, etc ... they're just "around 10lbs, around 20lbs" and I've used a good actually-calibrated scale (at work, some commercial business with calibrated scales that you can access, whatever) to weigh them and wrote their weights in sharpie on a piece of tape stuck to the objects. Ideally you'd go for around 10% increments. If the scale can weigh 400lbs, that would be every 40 lbs or so. But it really doesn't matter as long as you have enough good points around the range you truly intend to measure, and then a few outside of that target range at semi-regular intervals.
For my 0.1mg-resolution mass balance I have some actual calibration weights, but they're a relatively affordable OIML "M1" class, and did not come with expensive calibration certificates. The OIML tolerance ratings go E1, E2, F1, F2, M1, M2, M3 (from best to worst). For a 100g test weight, M1 precision gets you +/- 0.005g, guaranteed, for $50 ($135 if you want a calibration certificate). E1 gets you +/- 0.00005g at 100g test weight, for $500 ($1200 with cal cert). For smaller calibration weights like 10mg you'll generally want to go a step up from M1 (+/- 0.25mg) to F2 (+/- 0.08mg) for about $27.
For temperature, it's a bit trickier because the only "true" temperatures you can create are -6°F/-21°C and 228°F/109°C. If these temperatures are helpful to you, you can create them by pouring shitloads of salt in water and stirring+heating it until no more salt will dissolve and you just have a pile of salt in the bottom of the container. You can try to go for "0°C/100°C" using distilled water and it would probably be close enough but you can't know it exactly unless you use super pure de-ionized water and use extremely absurd lab technique (usually involving washing your glassware and tools with de-ionized water over and over for several days straight to get rid of trace contaminants).
So instead, to get "true" temperature in the range I care about, I use some thermocouples attached to a high-quality multimeter or oscilloscope. Then I calibrate these thermocouples using the method above, and average their reading for the oven temperature. This works and extrapolates well enough outside the range of calibration because the error of a thermocouple is basically guaranteed to be a very linear error.
In this link[0] topics 1-6 ("weeks") get into the fine details of all this and provide some worksheets/excel sheets already made up for this type of thing. If you're really getting into the weeds with this, understanding propagation of error[1] really helps but is super unnecessary for 99% of people unless they're doing actual engineering.
0: https://pages.mtu.edu/~fmorriso/cm3215/laboratory_exercise_s...
1: https://pages.mtu.edu/~fmorriso/Pintar_Error_Analysis_or_UO_...
The entire system is too complicated, and the CGM too variable in accuracy, for such calibration to work in the way I think you are suggesting.
Each time the CGM is applied, the situation is different because of the exact position and various other factors. And the CGM is not 100% consistent.
You do/can calibrate the CGM as needed. For example, when the CGM first activates, standard practice is to check with a fingerprick to see how accurate the CGM is this time and (sometimes) calibrate. (As noted in other comments, the CGM and fingerprick are not detecting exactly the same thing.)
And the next time you apply the CGM (we use a Dexcom G6, which is changed every 10 days), any previous calibration is irrelevant. There's a lot of variability and many factors that can affect results (exact location, scar tissue from previous CGM application, recent exercise, a recent hot shower, etc.)
(I didn't explain that well, but hopefully you get the idea.)
This is highly personal thing it is apparently very inaccurate for some people, I've never been below or over dangerous levels without it giving a warning. What has happend once or twice over the decade I've used it is that it will get stuck in a bad reading, so you do not see the variations. It has always got unstuck when I've gone below 3.5 mmol/liter or so.
It actually may actually be the other way around, at least for newer CGMs.
Try doing a few fingerpricks in a row. The variability will surprise you!
Another reason they are sometimes different is because there is a lag in the CGM data. It's estimated the lag is about 12 minutes.
Apart from the latency of diffusion from bloodstream to interstitial fluid (and the lower levels in the interstitial fluid) the FDA requires that consumer devices be with 20% of the venipuncture level.
That means a lancet poke can be quite different from a meter like the freestyle, and both can be quite different from the level in your veins that a lab would get. So if your level is 200 one device can read 240 and the other 160 and both can be considered “correct”.
I found that the freestyle libre 2 and libre light are characteristically low while the FS 3 is characteristically high. So I use them for the shape of the curve, and that is useful.
There is generally a latency of a few minutes between blood and interstitial fluid (the CGM) readings- up to 15 minutes. You may find if you account for latency your consistency between the two increases
What's the lifetime of a single device? Are you supposed to remove it before a shower and reapply it later?
No, it's mostly water proof. You wear it through showers and even swimming for 2 straight weeks. The adhesive is pretty good; rarely does it come off on its own prior to say, a week and a half in.
It holds 8 hours of data (1 reading per minute) and you can just hold up your phone to read the last 8 hours of data for your overall data.
thanks for the reply!
What symptoms would one have to present for an "online prescription mill"/"virtual care provider" to prescribe a CGM? I'm fascinated by this and would love to try it out but I don't want to bother my family doctor with this.
The only symptoms needed are a pulse, the ability to type out a credit card number, and availability for a sham phone call. It's virtually impossible to not get prescribed one from a mill.
How much would a month or two cost me if it was out of pocket? I wouldn't mind doing it for science.
That's not how it works, at least for the Freestyle Libre 3. The cross section of the needle has C shape rather than a O (technically I believe it's called a cannula). When you remove the applicator that C shape allows the needle to be removed through the hole at the top of the sensor, and only the flexible filament stays I your arm.
I belive he called the flexible filament "tube" and that you are both saying the same thing. Ie skin stays open (albeit in very tiny spot where the filament is sticked in)
Same, but my doctor pointed me to a promotion for a free sensor. It did require a prescription, but since I don't have diabetes, it's not covered by insurance.
Trying to get it filled and picked up was slightly annoying as the pharmacy initially did not want to fill it without some prodding, and I waited a while for them to figure out how to get the promotion billed.
I would love to see the results of that!