I've been using a CGM on and off for the last year, and it has given me a whole new perspective about food and nutrition.
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].
> 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 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.
Etheryte · 6h ago
Large glycemic spikes are are an issue, but the problem is not obesity. Obesity is concerned with calories in and calories out and our current obesity epidemic is largely attributed to the fact that we eat more calories and move less. Most other discussion points are secondary to that fact. Glycemic spikes on the other hand are linked to increased insulin resistance, heightened risk of diabetes, cardiovascular disease and so on. The two are linked, but not the same problem.
alexey-salmin · 5h ago
> Glycemic spikes on the other hand are linked to increased insulin resistance, heightened risk of diabetes, cardiovascular disease and so on.
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.
Etheryte · 2h ago
The risks related to glycemic spikes are a widely accepted fact in the medical community, it's not even remotely close to being a controversial opinion. See [0], [1] and [2] for a start, but really, there's a very wide body of research on this matter along with ample evidence.
I only casually follow these things, but my understanding is that interest in glycemic spikes is not really about obesity or fat at all, but more about diabetes-related issues, insulin resistance I think.
mathgeek · 5h ago
There's a popular subculture moment happening where non-diabetic folks are tracking their glucose since it's now possible to do without great expense. Similar to recent trends with step counters, heart rate monitors, etc. The necessity of tracking for diabetics has led to the opportunity for others.
bboygravity · 7h ago
The difference is corn syrup (in everything) vs sugar from sugar beets. Corn syrup has way more calories por unit sweetness.
WesolyKubeczek · 1h ago
> much like the previous "common sense" wave of "fat makes you fat" that led several generations into a dead end.
Fat does make you fat, in the sense that most of the fat in the body does come from dietary fat, but the mechanisms of this are way more nuanced than popular brochures back from "red meat kills" era would lead you to believe. Insulin itself doesn't singularly make you fat either, despite "bro science", again, there's more nuance. CICO works, but again, there's nuance to that too.
> My weight is stable but each time I go to US for a couple of weeks I bring back 3-5 extra kilos.
One thing I noticed immediately was that the bread in the US was very uncomfortably sweet, so much so that I'd put it into "pastries" category. Bought a loaf of "farmer's bread" at Trader Joe's, and while maybe not "pastry sweet", it was still in the dessert territory. Why does it take so much sugar to bake ordinary bread? I blame imperial units :-)
lurking_swe · 5h ago
i’m confused why you considered this healthy?
> 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.
adrian_b · 4h ago
White bread has a bad carbohydrates per protein ratio, but nonetheless it has a much higher protein content than almost any other cereal (i.e. except oats) and a much higher protein content than anything else with a comparable price.
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.
Otherwise, I agree with what you have said.
White bread could be combined with something that contains mostly proteins, possibly with fat, e.g. chicken breast or eggs, but then bread retains no advantages from its higher protein content (except of lowering the total cost of the food), so it should better be replaced by a healthier source of carbohydrates, i.e. maize or rice.
lurking_swe · 4h ago
i’m not a licensed nutritionist so i’ll defer to the experts. My recall on the details is not the best, simply what i remember from a few nutritionist sessions my wife had. :)
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 / trader joes.
adrian_b · 4h ago
By "cereal" I have meant cereal plants, i.e. wheat, rye, barley, oats, rice, maize, millet, sorghum and so on, in their raw ingredient forms, i.e. as grains, meal or flour form.
Cereals have been the main sources of energy in human food for the last ten thousand years, and among them wheat (because oats is only a minor crop) has also been a non-negligible source of proteins during all this time.
I have not referred to "breakfast cereals", which are the most obvious example of garbage food provided by industrial production.
(Many decades ago, there has been a time when I was too focused on professional problems and too careless about health and nutrition, and for a long time I have been eating some Nestlé breakfast cereals. After realizing the errors of my ways and blacklisting breakfast cereals, together with other junk food, like fruit juices or fruit yogurt, I was surprised by the quick improvements brought by this decision.)
lurking_swe · 4h ago
oh i see. I’d probably refer to that category as simply “grains” or “cereal grains”.
I’m in agreement!
ajb · 5h ago
Dried mangoes don't have fibre? How does drying them remove it?
fnands · 5h ago
They do have fibre, but a large part of (non-dried) mangos are water. If you remove the water, then the sugar density per volume/weight goes up a lot.
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.
lurking_swe · 4h ago
thank you for catching that, i misspoke regarding the fiber. My bad.
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.
ajb · 1h ago
Makes sense. Perhaps you were thinking of juice.
rglynn · 5h ago
I thought the same, seems obvious to me but I think a lot of people are still following the food pyramid and "all fat is bad" propaganda.
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.
tshaddox · 4h ago
Why is butter an unhealthy fat?
adrian_b · 3h ago
As another poster has said, due to it high content of saturated fat. Butter remains healthier than butter substitutes, e.g. margarine.
Small amounts of butter should not be a cause of concern, but only when butter or other dairy products are the major source of fat for someone.
As a personal anecdote, I believe that the composition of the fat one eats is very important for cardio-vascular health, because some years ago I had been diagnosed with incipient atherosclerosis.
This has scared me, so I have analyzed what unhealthy habits I might have had. At that time, I was eating very large quantities of dairy products. I could not identify anything else that was suspicious, so I have stopped eating dairy (except whey protein or milk protein, which are fat free) and I have ensured from that day on, that more than 90% of my daily intake of fats comes from a mixture of vegetable oils where oleic acid is dominant and essential fatty substances are in adequate amounts.
After a year, I no longer had any symptoms of atherosclerosis and there were also other obvious health improvements, because some signs of bad peripheral circulation, e.g. cold feet, had also vanished.
Few things in human nutrition are certain, due to the impossibility of doing experiments with humans, which could result in death or permanent health problems.
Nevertheless, it is most likely that fat should provide a good fraction of the total amount of energy, i.e. between 1/4 and 1/2, e.g. around 1/3, and the fatty acid profile should be thus that monosaturated fatty acids, i.e. mainly oleic acid, must be dominant.
Examples of food sources with fats where oleic acid is dominant are: high-oleic sunflower oil, olive oil, avocado oil, several kinds of nuts, e.g. cashew nuts, almonds, hazelnuts, pistachio, peanuts.
While such a fat with oleic acid must provide most energy, there must also be fat sources which provide essential fatty substances, e.g. linoleic acid, vitamin E, omega-3 fatty acids. (As an example of healthy daily intake, I cook my own food and most of the fat comes from the oil I mix into food after cooking, which for a day contains 50 mL of high-oleic sunflower oil or of EV olive oil + 20 mL of classic cold-pressed sunflower oil + 10 mL of cod liver oil. The cold-pressed sunflower oil is for linoleic acid and vitamin E, the cod liver oil for DHA, EPA and vitamin D.)
lurking_swe · 4h ago
Butter is primarily saturated fat, it’s often considered unhealthy due to its potential to raise LDL cholesterol and increase the risk of heart disease. Nothing wrong with butter - in moderation. And it’s great to get healthy fats into your diet!
Healthy fats are monounsaturated and polyunsaturated fats (“unsaturated”). Found in things like nuts, olive oil, avocado oil, fish, etc.
Llamamoe · 6h ago
> 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.
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.
DoingIsLearning · 7h ago
> 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.
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?
dbbljack · 1h ago
highly interesting!
yegle · 6h ago
For me the best insight learned from wearing a GCM is that a cardio exercise with 150bpm heart rate for 40min+ is probably not healthy. I would easily see my glucose level drop to below 80 mg/dL (5 mmol/L) 30min into the exercise. I always thought the exhaustion towards the end of my exercise was due to normal fatigue, and never thought it was caused by hypoglycemia.
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.
Youden · 5h ago
Rather than show that such exercise is unhealthy, I think it simply shows you need to consume some glucose during.
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.
defyonce · 2h ago
this, 100% i've been running 35km while fasted for 36 hours, and it is way more difficult than when you allow yourself to eat a snickers on the way.
now i am running my weekly half-marathons with something sweet, and it has been awesome. Like really no big deal.
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).
sdpy · 4h ago
There is also an open-source project Nightscout (CGM in the Cloud) which supports Android and iOS: https://github.com/nightscout
bix6 · 8h ago
I believe these cheaper devices are not very accurate ie accuracy range of 20% which is a fairly wide window. I’ve also heard there are many things that can impact your glucose even with the same meal like time of day, exercise, stress, sleep, etc. So if you actually want to find the patterns you’d need the expensive CGM over many months.
friendzis · 7h ago
Does not really matter.
You are interested in the trend, not absolute numbers, anyway, which, aside from having some "propagation delay", tracks blood glucose pretty well.
loremm · 8h ago
Is that true? I have no perspective but it's relied on by diabetics and if since they can't regulate it themselves, if the readings are off and they gave themselves insulin, they would know it is wrong. Maybe the OTC ones is different than the diabetic one but I didn't think so
nmehner · 7h ago
As a diabetic having alarms is the most important thing. Measurements are not that accurate (neither is the finger prick method: If sometimes get a difference of 20% comparing two measurements from both hands). But also the "ok" range of 3.8 mmol/L to 10 mmol/L is quite large and levels can rise/drop 20% in minutes. So it is still quite helpful.
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.
djur · 8h ago
Stelo is basically just a consumer packaged version of the Dexcom G6, and in both cases they warn you to use a finger stick to verify unexpected readings. But finger sticks can be really inaccurate, too. For many diabetics it's not a life-or-death matter (only 1 in 4 type 2 patients end up using insulin), and the important thing is the trend over time.
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.
bix6 · 7h ago
Most T1Ds I know use a CGM now as they are much more accurate than they used to be. But they are expensive so insurance generally covers for T1D but not T2D. You can always double check with a finger stick though as that uses blood instead of interstitial fluid. My friend uses a Tslim which uses a CGM to adjust her insulin automatically.
privatelypublic · 8h ago
They're not any different. CGM's have issues- sometimes need to be calibrated against a finger stick (officially, they always need to be)
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.
No comments yet
utopcell · 8h ago
> accuracy range of 20% which is a fairly wide window
what backs this factoid?
bix6 · 8h ago
I’m having a hard time finding a proper comparison table but the top end CGM systems now seem to be around 8% MARD. This study is for BGMS but it shows a range of 2% to 20%: https://pmc.ncbi.nlm.nih.gov/articles/PMC9445334/
guerrilla · 7h ago
It doesn't need to be accurate, just consistent.
WatchDog · 7h ago
I've been using "freestyle libre" devices on my diabetic cat, but they are quite expensive(~$110 AUD), and typically don't last the whole 14 day period before failing. Although I imagine they are much more reliable on a human.
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.
> it doesn't seem like the BOM is the main factor in the price of existing CGMs anyway
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
mlsu · 6h ago
And on R&D; the QC bar for software and manufacturing is much higher. Every process has validation testing. So it is expensive both in R&D and manufacturing.
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.
mondocat · 5h ago
I wore a monitor for two weeks. As someone who basically does not eat processed food, including sugar, and has 4-5 meals a day always including vegetables/fiber it was not obvious that what I ate had any reliable impact on the count. It would go up and down seemingly at random throughout the day and night. The highest and most reliable spikes came when I was lifting weights. Likewise cardio, especially high intensity cardio made it drop to its lowest levels. The most interesting outcome was that the late afternoon hanger I often felt was not associated with a dip (or change at all) in blood glucose as I expected it would be, so that remains a mystery.
randomcarbloke · 5h ago
as someone who eats relatively healthily but has no problem consuming processed foods (but tends to avoid excessive sugar), when I wore a cgm out of curiosity it was very clear that such a device offered me nothing, as a non-diabetic, non-pre-diabetic person the data showed that the body responds in line with input never exceeding tolerances.
It was impressive just how uninsightful it was, I love quantifying my workouts, my nutrient intake, etc, but the cgm added absolutely nothing.
cigs645 · 4h ago
CGMs are a great but if you wish to lose weight you have to create a calorie deficit as opposed to a surplus harder to do in our carbs heavy, sugar loaded, ultra processed foods dominated diets which are extremely unhealthy for us.
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, chronic inflammation, kidney disease, nerve damage, and vision loss). Chronic inflammation also thought to have a direct link with cancer
leakycap · 9h ago
The author's mention of the Hawthorn Effect fascinated me; I hadn't considered that with devices your care team can monitor.
It will change a lot of lives when some device that doesn't draw blood can continuously monitor glucose, like a smartwatch.
sdpy · 3h ago
That would be a game-changer for so many people. We're already getting close, though. Those CGMs like Dexcom don't actually test blood; they check interstitial fluid. There's a 5-15 minute delay, but still way better than finger pricks all day.
Non-invasive monitoring is still tricky. There’ve been some interesting attempts—like GlucoWatch back in the early 2000s, which used mild electrical currents, but caused skin irritation and never really caught on. Others have tried optical monitoring, radio waves, ultrasound, and even heat-based sensors. Feels like we’re getting closer, just not quite there yet.
shreezus · 7h ago
I believe we will see integrated optical glucose sensors in a popular consumer wearable fairly soon.
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).
privatelypublic · 8h ago
Pretty sure optical glucose is already a thing- it's just not very accurate yet.
Great resources. It seems we'll see BP monitoring integrated in a mainstream base smartwatch before we'll get optical glucose monitoring.
leakycap · 6h ago
I have used my phone camera to determine blood pressure, but I have yet to see a common consumer device with optical glucose monitoring.
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.
ViscountPenguin · 7h ago
Is there any actual data on the long term use of these devices in non-diabetics?
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.
randomcarbloke · 5h ago
I think it's definitely geek-bait, I wore one for a few months and would say that unless you have diabetes/pre-diabetes it's a waste of time.
lame-robot-hoax · 4h ago
It is geek bait — most people read too far into these “spikes” and cut out healthy foods in doing so. It’s taking literally one metric as gospel which is moronic to be frank.
imjonse · 7h ago
The author does not seem to go into details, so I am curious what actually surprising conclusions can be drawn from wearing one of these devices?
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.
Llamamoe · 6h ago
Pizza is much more nutritionally complete than you'd think, especially if it has meat(or beans, for some reason), the only real problem is people eat SO MUCH at a time.
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.
petesergeant · 5h ago
> White rice is basically pure carbs with barely any nutrients.
I am reasonably sure carbohydrates are nutrients.
jaggs · 6h ago
One of the more interesting findings is the impact of combining different food intakes at the same time. It can have a significant effect in lowering spikes.
utopcell · 8h ago
I share the author's enthusiasm about GCM devices. I am also finding that I need to change the over-patch long before the 15-day window because it gets messed up. I've found these [1] quite useful.
In a couple of cases, meals that I thought would be fairly healthy (or at least not terrible) were pretty terrible. There'll be some things that I'll avoid eating more than I had before.
Someone chime in with what they think these might be! Should I be eating less broccoli?
yegle · 7h ago
King's Hawaiian Roll.
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.
martind81 · 7h ago
What CGM device would you recommend for a first try?
stkhlm · 1h ago
Which ever you can get from Dexcom or Abbott. They're pretty good all of them.
Dexcom Stelo is probably the easiest to get a hold of, and the one talked about in the article too.
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.
thor-rodrigues · 7h ago
What I find absolutely infuriating is that Abott (Freestyle Libre 1-3 devices) region locks their monitoring app depending on your region.
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.
qsi · 5h ago
Is that because Brazilian regulations prohibit it? Or lawyers being too cautious?
ars · 7h ago
I wore one, but had some trouble with the glue, by day 8 or so it seemed like it was on the verge of falling off, so I added some medical tape which annoyed my skin.
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.
stkhlm · 6h ago
Some people do have a lot of issues with the adhesive and skin reactions. I am lucky and don't have that.
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.
duskwuff · 7h ago
> I suspect these devices will never go beyond 14 days at a time simply because of the glue issue.
The sensor chemically wears out over time too - the time limit is based on how long the manufacturer can guarantee good readings for.
dbbljack · 54m ago
if you don't need alerts for extreme high/low, i don't see the value of cgm monitoring... starch/grain/sugar spikes insulin, protein gives gentle raise within 3-5 hours, fat does next to nothing and does in around 7-9 hours. mixing a bunch of fibre/fat/protein into your starch and sugar makes the insulin spike less intense...
what are you guys learning about your super special non diabetic bodies that you can't learn with a $5 book of glycemic indices or a casual afternoon reading basic diabetes dieting advice?
cynicalsecurity · 4h ago
If you don't have diabetes type 1 or type 2, or temporary diabetes related to pregnancy, then you don't really need a CGM. CGM is a life-saving tool for people with diabetes type 1 mostly.
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.
mulle_nat · 4h ago
People should get on the bike and start cycling for real (like burn 200W an hour). Their perception of glucose will flip 100%. Suddenly glucose is like the fuel to your body, that you can't cram enough into. Which means white bread in the morning, croissants (and coca cola with sugar) will be your friends. Quite frankly a much better lifestyle.
painted · 1h ago
until you realize the sugar is also bad for your teeth, for example
hyperbolablabla · 7h ago
> "i would be amiss"
Huh, never seen that typo before. Should be "remiss"
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.
[0] https://cardiab.biomedcentral.com/articles/10.1186/s12933-02...
[1] https://diabetesjournals.org/care/article/38/12/2354/29088/L...
[2] https://www.sciencedirect.com/science/article/pii/S026156142...
Fat does make you fat, in the sense that most of the fat in the body does come from dietary fat, but the mechanisms of this are way more nuanced than popular brochures back from "red meat kills" era would lead you to believe. Insulin itself doesn't singularly make you fat either, despite "bro science", again, there's more nuance. CICO works, but again, there's nuance to that too.
> My weight is stable but each time I go to US for a couple of weeks I bring back 3-5 extra kilos.
One thing I noticed immediately was that the bread in the US was very uncomfortably sweet, so much so that I'd put it into "pastries" category. Bought a loaf of "farmer's bread" at Trader Joe's, and while maybe not "pastry sweet", it was still in the dessert territory. Why does it take so much sugar to bake ordinary bread? I blame imperial units :-)
> 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.
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.
Otherwise, I agree with what you have said.
White bread could be combined with something that contains mostly proteins, possibly with fat, e.g. chicken breast or eggs, but then bread retains no advantages from its higher protein content (except of lowering the total cost of the food), so it should better be replaced by a healthier source of carbohydrates, i.e. maize or rice.
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 / trader joes.
Cereals have been the main sources of energy in human food for the last ten thousand years, and among them wheat (because oats is only a minor crop) has also been a non-negligible source of proteins during all this time.
I have not referred to "breakfast cereals", which are the most obvious example of garbage food provided by industrial production.
(Many decades ago, there has been a time when I was too focused on professional problems and too careless about health and nutrition, and for a long time I have been eating some Nestlé breakfast cereals. After realizing the errors of my ways and blacklisting breakfast cereals, together with other junk food, like fruit juices or fruit yogurt, I was surprised by the quick improvements brought by this decision.)
I’m in agreement!
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.
Small amounts of butter should not be a cause of concern, but only when butter or other dairy products are the major source of fat for someone.
As a personal anecdote, I believe that the composition of the fat one eats is very important for cardio-vascular health, because some years ago I had been diagnosed with incipient atherosclerosis.
This has scared me, so I have analyzed what unhealthy habits I might have had. At that time, I was eating very large quantities of dairy products. I could not identify anything else that was suspicious, so I have stopped eating dairy (except whey protein or milk protein, which are fat free) and I have ensured from that day on, that more than 90% of my daily intake of fats comes from a mixture of vegetable oils where oleic acid is dominant and essential fatty substances are in adequate amounts.
After a year, I no longer had any symptoms of atherosclerosis and there were also other obvious health improvements, because some signs of bad peripheral circulation, e.g. cold feet, had also vanished.
Few things in human nutrition are certain, due to the impossibility of doing experiments with humans, which could result in death or permanent health problems.
Nevertheless, it is most likely that fat should provide a good fraction of the total amount of energy, i.e. between 1/4 and 1/2, e.g. around 1/3, and the fatty acid profile should be thus that monosaturated fatty acids, i.e. mainly oleic acid, must be dominant.
Examples of food sources with fats where oleic acid is dominant are: high-oleic sunflower oil, olive oil, avocado oil, several kinds of nuts, e.g. cashew nuts, almonds, hazelnuts, pistachio, peanuts.
While such a fat with oleic acid must provide most energy, there must also be fat sources which provide essential fatty substances, e.g. linoleic acid, vitamin E, omega-3 fatty acids. (As an example of healthy daily intake, I cook my own food and most of the fat comes from the oil I mix into food after cooking, which for a day contains 50 mL of high-oleic sunflower oil or of EV olive oil + 20 mL of classic cold-pressed sunflower oil + 10 mL of cod liver oil. The cold-pressed sunflower oil is for linoleic acid and vitamin E, the cod liver oil for DHA, EPA and vitamin D.)
Healthy fats are monounsaturated and polyunsaturated fats (“unsaturated”). Found in things like nuts, olive oil, avocado oil, fish, etc.
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.
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?
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.
now i am running my weekly half-marathons with something sweet, and it has been awesome. Like really no big deal.
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).
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.
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.
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.
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what backs this factoid?
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...
[1]: https://www.rightest.com/global/rightestifree2cgm/
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.
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, chronic inflammation, kidney disease, nerve damage, and vision loss). Chronic inflammation also thought to have a direct link with cancer
It will change a lot of lives when some device that doesn't draw blood can continuously monitor glucose, like a smartwatch.
Non-invasive monitoring is still tricky. There’ve been some interesting attempts—like GlucoWatch back in the early 2000s, which used mild electrical currents, but caused skin irritation and never really caught on. Others have tried optical monitoring, radio waves, ultrasound, and even heat-based sensors. Feels like we’re getting closer, just not quite there yet.
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).
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.
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.
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.
[1] https://www.amazon.com/dp/B0C4PKMJTN
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.
Dexcom Stelo is probably the easiest to get a hold of, and the one talked about in the article too.
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.
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.
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.
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.
The sensor chemically wears out over time too - the time limit is based on how long the manufacturer can guarantee good readings for.
what are you guys learning about your super special non diabetic bodies that you can't learn with a $5 book of glycemic indices or a casual afternoon reading basic diabetes dieting advice?
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.
Huh, never seen that typo before. Should be "remiss"
I think it is fine. It would be remiss of me to say otherwise.