I think you could have a point at around 100-105 baseline but 120 seems too 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.
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.
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.
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.
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.
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.
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.
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.
Note: This is pure speculation, and I'm not claiming to know anything more than passing knowledge about diabetes.
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.
(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.
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.