[pedalpete]

Blood glucose is dependent on more variables than just what you eat.

Decreased sleep slow-wave activity (not just sleep time, but the actual restorative function of sleep) significantly decreases next day insulin response [1].

This is my area (I work in neurotech/sleeptech), but other things that come to mind are changes in changes in gut biome, which can be altered by previous meals, and I assume is always in flux (not my area of expertise), hormonal changes, I'm sure there are others.

However, the conclusion that it undermines the CGM measurements. In fact, I think this makes CGMs more valuable, not less. For those without diabetes, I always thought you'd use the CGM for a few weeks, figure out what your body responds to, and then sort out your diet.

This shows that it isn't that simple, and that we likely need to be monitoring more regularly. If my breakfast spiked my glucose unexpectedly, that may be a signal that I should change my lunch in order to reduce the likelihood of another spike. It becomes about constant management, rather than a 1 time look under the hood.

https://doi.org/10.1016/j.sleep.2022.03.005

[esperent]

> For those without diabetes, I always thought you'd use the CGM for a few weeks, figure out what your body responds to, and then sort out your diet.

This was my plan sometime in the next few months.

I think it's still a valid plan, just with some caveats. Anyway due to cost and annoyance I'm unlikely to wear a CGM for more than a couple of months. But that should be enough time to get usable data - like all body tracking data, I'll end up using it as guidance rather than rule.

The caveats are that I'll also need to track my sleep and workouts during that time and carefully look for patterns in the data related to all three.

I already know sleep and workouts are strongly correlated and not always in the way you'd expect. I did a strong HIIT class at 6pm last night, and due to a bit of crunch on personal projects it was my first proper workout in a week. My sleep tracker (Galaxy Watch 6) gave me a very poor sleep and energy score. 61/100 for sleep, 69/100 for energy. I normally score high eighties to low 90s in both.

These scores usually but not always match with my actual feeling. But today I also feel tired (it's 8am here now).

If I had a CGM, I'd also be keeping a strong eye out for unusual glucose response today.

This is more complex than I'd like it to be - I wish my body was as simple to read as just getting a single number like glucose response and making adjustments from that! But as a lifelong migraine sufferer who now has my migraines almost entirely under control by making lifestyle changes, I'm well aware that how my body responds is always a combination of many things. Stormy weather + ate cheese + slightly too strong coffee + stress from work = boom, migraine. Take away any one of those and maybe I wouldn't have got one. I fully expect my body's glucose response to be just as complex.

[Zanni]

Well, yes, but it's also pretty dependent on what you eat. From the article: "Additionally, the summarized study did not record the timing of snack and water consumption."

A carb-heavy snack before a meal is going to result in a radically different response than eating the same meal on an empty stomach. I'm glad they acknowledged it, but it feels absurd to publish with this headline if they didn't record snacks.

[gcanyon]

If a normal-weight person undergoes significant long-term sleep deprivation -- like >50% of nights on 4-6 hours of sleep over the course of decades -- what would the expected effect to be? And if the person's bloodwork nevertheless shows no particular signs of poor insulin response?

Asking for a friend.

[pedalpete]

Well, you're getting into measuring sleep by time, which is an antiquated idea that we need to move on from. I write about this on the affectable sleep blog [1]. We shouldn't be looking at time, but the restorative function of sleep, and we need to take each individuals restorative function as independent. The average diet recommends 2400 calories (I think), but you wouldn't say that if someone got only 2000 calories a day, they'd starve.

However, on a population level, it is known that shift workers have increased incidence of diabetes, heart disease, obesity, etc. Some of that likely comes down to socio-economic factors, but we can't ignore that daytime sleep or potentially even shifting schedules, is not as restorative as consistent sleep, regardless of sleep time.

I feel I haven't answered your question, but I think this is the best I've got.

[gcanyon]

Thanks for the effort!

[sinuhe69]

What about the famous breakfast? One prevalent theory among nutritionists is that the breakfast has huge influence on the insulin responses during the day: a low carb/no sugar, high protein and fat breakfast will not spike your blood glucose level and therefore will lead to a more moderate response to meal intake during the day as opposite to a high carb breakfast. I think the study should control this variable as well.

[apwell23]

> One prevalent theory among nutritionists

why don't they test it. should be easy create a study?

[apwell23]

i think oura ring wanted to combine cgm and sleep values. Not sure if they ever went ahead with cgm partnership.

[lytefm]

Yeah they bought veri.co last year and announced the integration of metabolic into their platform last week.

As the authors mention in the end, personalized nutrition based on CGM only makes less sense than also integrating sleep, stress, movement,... - which Oura is really good at.

[pedalpete]

They just announced CGM integration last week.