In the end though- it's still a bit of fungal extract painted onto an electrode, and an ADC that reads the value every so often. Like any other glucose monitor.
I've personally found my CGM to be really useful in understanding the effect of diet, sleep, stress, etc. on my blood glucose, like the OP says, but you definitely get some weird readings sometimes. Yesterday a new unit told me that my blood glucose dropped below 70 for 2 hours. It definitely didn't! After a while it got itself straightened out in time to scold me for eating some corn chips.
With the CGM there is also an additional delay of about 15 minutes in the measurements. Mostly you want to be triggered when something strange happens and then you do a manual measurement to confirm.
A false alarm of low blood sugar is annoying, but it is a lot better than collapsing. You can relax a lot more if you know you will get an alarm.
what backs this factoid?
I discovered that a bunch of things I thought were reasonably healthy actually caused huge glycemic spikes -- e.g., white bread in the morning, croissants, dried mangos, excessive amount of fruits, etc.
I also discovered the importance of what you eat for your first meal in the day (either breakfast or lunch), or how to better order what you eat (fibers, fat and protein first, carbs last), light movement after eating reduces 20+ mg/dl, and more.
At this point I don't even need to wear a CGM every day; I can tell my glucose level just by thinking of what I ate earlier.
I still wear one when I'm traveling for work, as I know I'll have less control over food and calorie intake (airplane meals, restaurants, team lunches, etc).
ps: if you're interested in learning more even without using a CGM, strongly recommend "Glucose Revolution" [1].
[1] Glucose Revolution: The Life-Changing Power of Balancing Your Blood Sugar - https://www.amazon.com/Glucose-Revolution-Life-Changing-Powe...
I wonder if this amounts to optimization of an easy-to-measure and reasonably-looking but incorrect metric, much like the previous "common sense" wave of "fat makes you fat" that led several generations into a dead end.
You assume above that glycemic spikes are unhealthy which I think was never proven for the general population. Eating too much sugar or eating too much in general is bad, but I'm not aware of evidence that croissants kill you if you eat reasonably.
Another thing to note: one of the potential suspects in the obesity epidemic is HFCS, and fructose doesn't actually cause glycemic spikes. If this turns out to be true, then parallels with the "fat makes you fat" theory become uncannily strong.
I tend to think this could be the case because it matches my personal observations. I moved to France a few years ago and the amount of croissants I and people around me consume is at the stereotypes level. My weight is stable but each time I go to US for a couple of weeks I bring back 3-5 extra kilos. Something is seriously different between the food here and there, and I don't think it's glycemic spikes per se.
How exactly are they linked? Is it the size of the spike, the length, the frequency? Does it matter at all if you don't overeat? What evidence exists to support it?
For instance, the plain white rice causes a huge glycemic spike but somehow it's the US facing both obesity and type-2 diabetes wave, not Vietnam.
I agree that linking glycemic spikes with insulin resistance is "logical" but without hard evidence it's worthless and it doesn't seem to agree with the reality I see.
Would be interesting to create some form of model of that and see how accurately you could 'guess' gliglycemia levels for a specific individual just by knowing biometric info and accurate food intake.
As in could you potentially appify your newly acquired intuition?
It's baffling that those things are considered healthy in the first place - white bread, pasta, rice, potatoes contain so much starch(which is rapidly broken down into glucose) that their glycemic index is higher than that of table sugar.
Likewise, the entire reason why fruit are tasty is because they're sugar bombs. The absorption is slightly slowed by cell wall digestion, and they have antioxidants, vitamins, etc. But still. It's sugar.
> I also discovered the importance of what you eat for your first meal in the day (either breakfast or lunch), or how to better order what you eat (fibers, fat and protein first, carbs last), light movement after eating reduces 20+ mg/dl, and more.
Having read science on the topic, you're extremely right on botr counts - limiting carbs in the first meal of the day moderates glucose spikes for the entire rest of the day, and moving after high carb meals is critical because muscles uptake glucose independent of insulin signaling, massively reducing the stress on your metabolism.
> white bread in the morning, croissants, dried mangos, excessive amount of fruits, etc.
white bread is basically 100% carbs (converts to sugar). croissants aren’t much better _and_ have unhealthy fat (butter). Dried mangoes pack the sugar of the fruit without much of the fiber and water (speeds up the processing of the sugar).
Healthy breakfast would be like 2 eggs with small slice of toast on the side. Or a small omelette with cheese and mushrooms and spinach. Or perhaps steel cut oats, with thin sliced banana.
Basically - real food that also not loaded with carbs and sugars. Carbs are OK if you actually need them (workouts, etc). Office workers don’t need lots of carbs.
Granted, “healthy” is a spectrum…some people would consider it a win to not smoke, drink soda, etc.
And you’re 100% right about eating fiber first. It greatly slows down sugar absorption/processing! And reduces the sugar spike. That’s an advanced tip most don’t know about.
This makes it easier to consume much larger volumes of dried mangos vs raw mangos. This basically goes for all dried fruits.
Eating three mangoes in a sitting feels like a huge amount of food. Eating three mangos worth of dried mango is pretty easy.
One other thing to be aware of is dehydrated foods are less satiating (lacking water). This makes it easier to eat more of them in one sitting and consume more sugar.
Although on a perhaps more humourous note: if bread, croissants and sugary fruit is considered a healthy breakfast, I'm dying to know what GP thinks an unhealthy one is.
So saying that it is basically 100% carbs is definitely wrong. Good wheat flour for bread has about 1/8 of its weight as proteins, while e.g. maize meal has only about 1/16 and rice between 1/16 and 1/12, but typically towards the lower end of that interval.
White bread is the cheapest source of proteins, but it has the serious disadvantages that its proteins are digested incompletely by most people and the proteins come with too much carbohydrates. The carbohydrates, i.e. the starch, can be removed totally or partially by making a dough and washing it, but that consumes a lot of water and time.
What i do know is white bread for breakfast wouldn’t be considered healthy by any nutritionist i’ve spoken to. Unless it’s paired with something else like eggs. And comparing it to cereal feels absurd, since cereal is loaded with extra sugars on purpose. Except for plain cornflakes and a few healthy brands at whole foods.
TL;DR:
As a healthy, non-diabetic adult I wore a Continuous Glucose Monitor (CGM) to measure my blood sugar for two weeks
The sensor was convenient to use and painless to apply, and was barely noticeable during the two weeks it was on my arm.
In analyzing my blood sugar levels, I learned a lot about my body’s response to different foods and exercise; I could identify some foods that spike my glucose.
Two weeks is too short to make detailed improvements to my nutrition in order to stabilise glucose levels — further monitor and experimentation will be needed.
I've stopped using them because it's just a bit too expensive, and my cat's diabetes is more stable now.
I opened up a freestyle libre 2, it has a EM9304 bluetooth SOC, and a TI RF430 NFC microcontroller, chatgpt deepresearch estimated the bill of materials to be about $5 USD[0].
Some companies[1] are developing reusable CGMs, the electronics are reusable, but the glucose oxidase probe, and applicator needle are still consumable. I'm not sure if that will bring the costs down much, it doesn't seem like the BOM is the main factor in the price of existing CGMs anyway.
[0]: https://chatgpt.com/share/686225c7-11ac-8005-aa4a-f420415e21...
No. A huge reason for the cost is (1) costs in R&D but also (2) the customer service/replacement requirements/etc required for medical devices.
If you were diabetic, and had a prescription for these devices, you'd be able to call Abott/Dexcom and get a replacement to a failed device shipped to you overnight. If the device didn't last the fully spec'd lifespan, you'd be eligible for replacements... etc
Another thing is that these off the shelf CGMs don't really differ in quality to their prescription only counterparts, which have a pretty extreme risk profile (patient death or hospitalization if it spits out the wrong number). They use the same parts so those costs are inherited.
I suspect these devices will never go beyond 14 days at a time simply because of the glue issue. My skin was also pretty irritated once I removed the device, with some blood where the device sat.
If you chose to wear one, especially in the summer, work very hard at removing all oils from your skin before you apply it. Soap and water (preferably real soap, not SLS), and then alcohol to get everything.
I discovered that my wake/sleep cycle affected my blood sugar as much as, or even more than, what I ate.
The sensor chemically wears out over time too - the time limit is based on how long the manufacturer can guarantee good readings for.
I use an Anubis, a modified Dexcom G6, (https://www.loopandlearn.org/anubis/), which allows up to 60 days of wear. Although realistically I've never gone over 25 days. This is with adding over patches as the adhesive starts to fail though. The one I'm wearing right now is on day 18 and still doing great.
After day 10-12 I also start to do daily checks with a blood glucose meter to verify that the readings from the CGM are still correct.
It's open source and supports all CGM sensors that I know of.
It has the ability to "broadcast" your data to various destinations and has a built-in https server to export a quick summary view to share with your doctor. It also supports exporting to Abbot LibreView so your significant others can use the LibreView app to view your data.
Don't be intimidated by the UI: it's weird and seemingly outdated, but EVERY part of the UI has a dedicated "help" button that you can click and read for details.
Couldn't be happier since I ditched the Freestyle Libre app (it failed to open after an Android update).
Someone chime in with what they think these might be! Should I be eating less broccoli?
It doesn't taste like it contains a lot of sugars, at least not as sweet as other desserts like a cake. But two rolls (weight wise, very small amount) would send my glucose to sky high.
Huh, never seen that typo before. Should be "remiss"
I think it is fine. It would be remiss of me to say otherwise.
This feels like geek bait, imo. A nice simple metric to obsess over, and to optimise. With a super simple (therefore presumably wrong) biological model to back up it's worth.
It seems to be, that nothing particularly good has come of prior trends in quantified self-health (for regular consumers, pun intended, at least); and this seems to come packaged with a very real risk of orthorexia.
Croissants and muffins being unhealthy should be no surprise. I am more interested in findings like food that gets a bad rap being not that unhealthy and supposedly healthy food being bad.
People also refuse to understand that juice is basically sugar water with some extra flavor, vitamins, and antioxidants that don't change how unhealthy it is for you.
White rice is basically pure carbs with barely any nutrients.
Fastfood is heavily processed but often contains enough vegetables, meat, etc to not be that bad all things told.
I am reasonably sure carbohydrates are nutrients.
My father is T1 is uses the Libre CGM system for a couple years now. Libre users in the US and Europe can enjoy direct integration with their iOS devices, including constant updates and most importantly, notification alerts for dangerously high or low glucose levels, and it is even possible to share live updates of this with close family members or caretakers.
But none of this is available for my dad, as he lives in Brazil. Even though the product is same, he cannot download the iOS apps over the AppStore, as they are region locked.
Now I would exercise and closely monitor my glucose level, then adjust my intensity when it dip lower than 100 mg/dL (5.5 mmol/L). It made the cardio exercise much more bearable, and easier to stick to it as a daily routine.
There's a reason aside from taste that sports drinks all contain a helping of glucose. I can't recall if I saw them in the US but in Europe many supermarkets offer products like "Dextro Energy", which is essentially just a sugar tablet advertised to people who need glucose during sports.
It was impressive just how uninsightful it was, I love quantifying my workouts, my nutrient intake, etc, but the cgm added absolutely nothing.
I know I went from a 7.1 A1C(type 2 diabetes) to a 5.3 A1C(no diabetes) in a little over a month by going on a Keto diet while laying off the carbs and exercising regularly. If you don't CGM or not you'll end up like the almost 1/3 of the US population or 98 million Americans who are currently pre diabetic looking to join the 38.4 million who are already full blown diabetics a condition often called the silent killer for good reason (heart disease, stroke, kidney disease, nerve damage, and vision loss)
I was hugely ignorant of diabetes type 1 before my child suddenly was diagnosed with it. It's an absolute nightmare, a horrifying disease no one is taking about while there are millions of children affected by it worldwide - and the disease is spreading, getting worse every year. It's astonishing how many unknowns there are in this disease.
leakycap•4h ago
It will change a lot of lives when some device that doesn't draw blood can continuously monitor glucose, like a smartwatch.
privatelypublic•3h ago
nmehner•3h ago
Existing smart watches that claim to do this are basically garbage. Just use a random number generator instead.
Apple and Samsung are supposedly working on it: https://www.forbes.com/sites/davidphelan/2025/01/26/samsung-... But it seems to be hard and from what I have seen the new Galaxy Watch 8 won't have this feature.
leakycap•2h ago
leakycap•2h ago
I'm suggesting that it will change the world when it is an integrated part of something many/most of us buy and would eventually upgrade to.
shreezus•3h ago
I don't think they'll be as accurate as blood sensors, however they will be a game-changer for many people (pre-diabetics, or gestational diabetes etc).