[blindriver]

I've been diagnosed with Type 2 diabetes and wear a CGM. I find that my blood glucose spikes much later than what is suggested. For example, I might eat a meal and my blood glucose doesn't spike until after 2 hours. When it spikes, I see the body react with insulin and it drives my blood sugar levels down, so I'm not sure if I actually do have T2D or if this is just how my body works.

Another thing I've noticed is that if I eat a very rice-heavy meal, my blood sugar levels may rise throughout the night. I don't think this is insulin-resistance but rather my body digesting the rice. You can't expect the body to digest all the rice in 2 hours, can you, there certainly must be parts that are protected from the stomach acid until much later in the digestion process. So that feeds into the high blood sugar levels overnight in my opinion.

I think if anything, CGMs have opened up the idea of what diabetes really is and how different bodies handle blood sugar. I think I'm borderline T2D, not full-on T2D despite what my doctor says, and I've started wondering if my blood sugar has always been high, but normal for me. On average it's about 120 mg/dL, but I do see my body react properly to new sources of blood sugar and drive it back to "normal" levels, so the idea that I have insulin resistance doesn't make sense to me.

[UomoNeroNero]

I’m diabetic and manage it with a CGM and insulin pump (HbA1c at 6.8 after many years of struggles).

For convenience and my experiment, I eat practically the same meals at lunch every day, precisely weighed, always starting from very similar morning glucose levels, and strictly respecting timing and consistency.

I NEVER get the same response. Never. It’s an experiment I’ve been running on myself for a year. It’s useful for me, but for the diabetes team following me, “that’s not possible, there must be other factors, it doesn’t show, it’s the ‘CGM algorithm’” (a mystical object no one knows anything about, except that it’s supposedly intelligent).

This study is interesting. I hope this kind of information, this doubt, trickles down into the medical community. Even though I don’t have much hope. Maybe in years and years.

[nick3443]

Would be interesting if a non-diabetic person does the same trial, as a "control".

Note: This is pure speculation, and I'm not claiming to know anything more than passing knowledge about diabetes.

[nomel]

Do you see any relation to physical exertion of the day before/after? What about mental signals, like "I'm going to be walking a bunch tomorrow"?

[UomoNeroNero]

I am a developer and i work from home. In my experiment i ruled out “any kind of movement” :-D (no, i am not a bag of fat, only a lotto e “not in perfect shape”). But. I can confirm that lot of stress and lot of coffe have a big and misurable effect.

[lrhegeba]

thanks for "misurable". i'll steal this wonderful combination of miserable and measurable, i see lots of use in devops for it... ;-)

[Jarmsy]

I definitely see effects on my glucose the day after when I change my exercise routine, such as doing an extra LISS session. Anticipation of something stressful or exciting does also have an effect. I haven't noticed any effect from simply expecting more exercise later (without emotions attached). I believe a lot of this comes down to liver and muscle glycogen storage and release. (I'm T1)

[blindriver]

I think the “experts” thought they knew but CGM is showing they really don’t know.

Sometimes my blood glucose will be high-ish like maybe 135. Then if I drink some coke, ie pure sugar, it causes my blood glucose to spike and then my insulin kicks in and it drives it back down to 110-120. It’s as if the switch to turn on the insulin wasn’t turned on because there was a slow steady creep up of blood glucose and then it needed to be woken up.

The body sure is strange but one thing I do know is that CGMs are changing things for sure.

[wonder_er]

I do _not_ have any sort of insulin resistance, and have worn a CGM for a while, a few different times.

(Purchased sorta 'just for fun', to evaluate my own metabolic responsiveness. I wrote about it once: [0])

if I moved around much after eating, my muscles would "soak" lots of glucose from my blood and the insulin change would be relatively low. If it was something sugary and I then went to sleep, it would be a big slow rise for a few hours of blood sugar, then insulin would seem to be released, and it would decline a bit, then flatten, then decline, until it went back to a regular level. When waking up, it would often by around 70 mg/DL, and even if I eat zero carbs (or am full-on fasting!) it would bounce up/around during the day. I appreciated that my body seemed quite capable of doing whatever it needed to do to raise my blood glucose levels. (They always go up when exercising, for instance, even if no food is consumed)

I think everyone would likely find the data interesting, it's so freaky customized to yourself, it cannot help but be interesting. They're expensive, so I think buying even one sensor and wearing it for 2 weeks or however long is worth it.

[0]: https://josh.works/cgm

[zamadatix]

I'm a fellow type 2, be sure to talk more with your doctor about these points as such comments/questions are of things they should have explained very clearly the first time they said your sugar seemed high.

Type 2 "resistance" is about the quality of the response to high glucose levels, not the complete lack of a response to them. There shouldn't be a long buildup overnight in that scenario for a person without insulin resistance/deficiency and still having a measurable insulin response is normal/expected of all but the worst Type 2 diabetics. Yes, you're still digesting, but in individuals without diabetes the blood sugar peak occurs (and ends) well before digestion is finished because influxes of carbs can still be effectively managed by the insulin alone rather than by the lack of additional carbs to digest. If it were just that one's digestion were a lot slower than a normal persons then it should still result in a lower, but still quickly managed to baseline, peak.

You may well actually be prediabetic though, it just depends on the specific numbers for A1C/average & peaks combined over time and not the presence of a response itself. The recommendations between higher side prediabetic and lower side type II diabetic shouldn't be all that different in the end anyways though.

[chimeracoder]

> You may well actually be prediabetic though, it just depends on the specific numbers for A1C/average & peaks combined over time and not the presence of a response itself.

Just to clarify - A1C is itself an easily-measured proxy for diabetes mellitus, but it's itself a heuristic. There are groups for whom it is known that the "standard" A1C range is actually incorrect, because of confounding factors that affect the A1C measurement but are unrelated to the metabolic dysfunction or general sugar levels.

Your point is correct, though, that what OP is describing is consistent with diabetes, and the actual clinical recommendations for prediabetes and Type II diabetes are often the same, at least in the early stages.

[RHSeeger]

> I find that my blood glucose spikes much later than what is suggested.

I'm a type 1 and my blood glucose can response can vary wildly. Sometimes it can spike quickly (15-30 minutes), other times it can take 2, 3, or even 4 hours. The reverse is also true, in that insulin can sometimes effect me quickly, and sometimes it can take effect 3+ hours later. In general, when having a big meal, I'll take a "fairly large" amount of insulin, but not enough for the entire meal; then I'll take more[1] when my blood starts increasing into 200+ range. Otherwise, I risk it dropping because the insulin was having a "fast" day but the food was "slow".

My endo finds it weird, but we've gone over specific cases of it, including exactly what I ate, when, and what the CGM history for the day looked like. I'm just defective :)

[1] Note I'm not talking about reactively taking more insulin after the "right" amount turned out not to be enough (which is generally a bad idea). Rather, I'm talking about splitting what I know to be about the right amount... into 2 different doses.

[pixl97]

Also a T1D and yea, I know what you mean.

Physical activity, mental activity, and sickness can also massively effect dose.

On days I'm physically active I feel like I need less than half the dose of insulin then days I'm caught behind a desk. This said, high impact mental stress that requires lots of thinking can rapidly drop my glucose level.

And that's not counting being ill where my body will pretend like it's insulin resistant for hours then suddenly try to process it all at once.

[DavideNL]

2 other factors other than physical activity and stress that seem to impact insuline sensitivity:

1. Temperature (room / outside)

2. How well you’re hydrated

Regarding the *time* it takes for eaten Carbs/glucose to enter the bloodstream, it seems that simply standing/being postural often slows down digestion, while sitting/laying down (think of a couch potato watching tv) seems to increase digestion speed.

[mh8h]

Have you measured the lag time for your CGM?

Typically the glucose level in the interstitial fluid takes longer to respond to your food intake, and the GCMs measure that instead of the blood glucose level.

[bilsbie]

Interesting. What’s your a1c level ?

I think you could have a point at around 100-105 baseline but 120 seems too high.

[hinkley]

I just found out a friend was diagnosed with diabetes due to a sugar test while their a1c was still in the normal range. We’ve got a long way to go yet with diabetes research.

[cfu28]

I mean, it is well known that A1c has a 3 month (usually) lag time assuming no hemolytic states. Could have been just caught early depending on what you mean by sugar test

[hinkley]

No they already are in early stage fatty liver. This has been a long time coming and surprises no one. The only surprise is not failing the a1c.

[cfu28]

I guess I’m confused, A1c is a measurement used for diabetes, not fatty liver/nafld. Can absolutely be correlated with diabetes and elevated A1c but those are two independent things we seem to be talking about

[blindriver]

It's high, like 6.7-6.9. It doesn't make sense to me because that would suggest average blood glucose of over 150, but it's objectively around 120.

[nradov]

There is some genetic variability in the correlation between blood glucose versus HbA1c. The HbA1c test is essentially an integrator of blood glucose level over time but different people have different average red blood cell lifespans.

[majkinetor]

RBCs life span can vary between humans. That's why hba1c is not always the correct surrogate.

[gukov]

CGMs react slower and can be quite wrong compared to finger pricking.

[Aloha]

Slower yes - there is typically a 15-20 min lag time - not two hours.

[bobmcnamara]

Do you know if you do(not) have delayed gastric emptying?

[e40]

Usually T2D is diagnosed based on a fasting glucose test. I also recently worse a CGM because I was borderline T2D and wanted to know how various foods impacted my levels. My peak was about 2 hours after the meal, so about 1.5 hours and change, given the lag of the CGM.

I also found that sweets not only spiked my values but did so over a 6-12 hour period! That was shocking. I have not had dessert for 107 days because of it. I plan to do a fasting test (and A1C) in August to see how many values are. I hope they are much lower, but we'll see.

EDIT: also, popcorn with nothing on it but salt gave me a huge spike.

[zamadatix]

Popcorn (even plain air popped) is more carbs as a percentage of mass (~70%) than eating a bag of Hershey Kisses (60%) so it's no surprise. I've always found starches to be the bigger culprit of my spikes than sweets since it's relatively easy to overlook and much easier to consume a large quantity without thinking about it.