Category: Blood Glucose

Experiment Pre-Registration: Measuring the Effect of Sleep on the Blood Glucose Impact of Meals (Replication of Ilmo Stromberg’s Results)

Ilmo Stromberg just posted a fantastic write-up of 100 days of monitoring his blood glucose using a CGM. He had tons of interesting observations, but the three that stood out for me were:

  1. No correlation (R2=0.03) between average glucose and sleep score (Oura ring, R2=0.003)
  2. Slight correlation (R2=0.09) between last glucose value before sleep and deep sleep (Oura ring)
  3. Strong correlations (R2=0.36, 0.92, & 0.98) between total sleep the previous night and “meal scores” (a measure of the blood glucose impact calculated by the Veri app from the CGM data).

From my own data, I also haven’t seen a correlation between average glucose and time asleep, but I never thought to check impact on just meals to reduce noise in the measurement.

For the correlations with specific meals, Ilmo had a relatively small data set (3 meals, 4 datapoints each), but the effect was consistent and strong.

I’m interested to see whether I can detect the same effect. I eat a very consistent breakfast and relatively consistent lunch, so I should be able to get a statistically robust measurement in a relatively short time.

I’m pre-registering the experiment here for data quality & transparency and to get feedback on the experimental design.

Details

Experiment

  • Breakfast:
    • I will take 4.5u of Novolog (fast acting insulin, duration of 2-4h), wait 30 min., then eat 50g ketochow with 2 tbsp. of butter (website, BG testing).
    • This is my standard breakfast and insulin dosage and will be used every day.
  • Lunch:
    • I will take 3u of Novolog (fast acting insulin, duration of 2-4h), wait 15 min., then eat 50g ketochow with 2 tbsp. of butter (website, BG testing).
    • This is my standard lunch and insulin dosage when I’m not doing a food effect experiment. On days when I am doing a food effect experiment or otherwise need to deviate from this meal, I won’t record data.

Measurements

  • Blood glucose will be monitored using a Dexcom G6.
  • Sleep will be measured using the Oura Ring 3
  • For each meal, I will record:
    • Time of insulin injection
    • Amount of insulin injected
    • Time of meal
    • Any additional observations

Analysis

  • I will conduct an analysis after collecting 30 days of data. If the results are inconclusive, I will collect an additional 30 days of data and re-analyze.
  • Peak change in blood glucose and area under the curve will be calculated for the 2h after each meal.
  • Pearson R (with 95% CI) and p-value will be calculated for the following correlations:
    • Peak change in blood glucose vs. time asleep (breakfast & lunch)
    • iAuC vs. time asleep (breakfast & lunch)
    • Average daily glucose vs. time asleep (prev. night)
    • Average daily glucose vs. sleep score (prev. night)

Please let me know if you have any comments or suggestions on the experimental design.

I will start recording data immediately and will report out the results on March 12th


– QD

Experiment Pre-Registration: Testing the Accuracy & Convenience of Innovative/Interesting Blood Glucose Meters

A few weeks ago, I ran across the Pogo “all-in-one” blood glucose meter in this sub. I was intrigued by the concept of a meter that automated lancing, blood draw, and strip changing, so I tried it out. Unfortunately, I found it to be a less accurate and more painful than my trusty FreeStyle Lite meter.

There are a number of other meters I’m interested in trying out, so I decided to expand the study. I’m pre-registering the experiment here for data quality & transparency and to get feedback on the choice of meter and experimental design.

Does anyone have recommendations for interesting blood glucose meters they’d like to see me test?

Details

Meter Selection

To find blood glucose meters to test, I searched Google, Amazon, various diabetes forums, and posted to r/diabetes. I also looked at academic papers testing the accuracy of different meters, the most useful of which was a paper from Russell and co-workers. Based on this, I selected the following meters to test:

  • Control: FreeStyle Freedom Lite
    • This is the meter I’ve been using since I got diabetes ~10 years ago. It ranks 5th on accuracy in the paper from Russell and co-workers and requires very little blood, making it easy and quick to use.
  • Precision: Contour Next & OneTouch Verio Flex
    • These were the two most accurate and precise meters from the paper from Russell and co-workers.
    • The actual OneTouch meter from the paper was the VerioIQ, but that’s no longer available. The Verio Flex is a newer meter from OneTouch, so hopefully it’s as good or better.
  • Low-cost: ReliOn Premier
    • This is Wallmart’s low-cost meter. It didn’t perform well in the paper from Russell and co-workers, but it’s only $18 for 100 strips without insurance, so I’m interested to see how it compares.
  • Innovative Design/Functionality: Dario, Accu-Check Mobile, & Beta-Chek
    • All three of these have the meter, lancets, and strips contained in a single device, making carrying the meter much more convenient.
    • Pogo had the same promise, but was less accurate and more painful, so I’m really interested to see if these work better.
  • Meters that are of interest, but I can’t get: Beurer 50 GL Evo & Glucorx
    • These both look interesting, but are not available where I live. If anyone has a suggestion on how I can get them, I’ll add them to the experiment.

Experiment

  • I will test my blood glucose once per day for 15 days, rotating between three times: pre-lunch, pre-dinner, and before bed.
  • At each time, I will take 3 measurements with each meter and record the results from my Dexcom G6, along with any failed test strips and observations on convenience, pain, and other user experience.
  • This will result in 15 sets of 3 measurements for each meter, for a total of 45 measurements/meter or 315 total blood glucose measurements (more if I get additional meters).

Analysis

  • For each meter I will calculate the pooled standard deviation, bias (vs. Freestyle Freedom Lite), and mean absolute difference (vs. FreeStyle Freedom Lite).
  • All values will be reported with 95% confidence intervals & data will be visualized using Tableau.

Please let me know if you have any comments or suggestions on the choice of meters or experimental design.

The last meter should be arriving by February 13th, so I will report out the results on March 5th.


– QD

Blood Glucose Testing of Whole Foods: Initial Results & Request for Suggestions

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This post is an update on my experiments measuring the effect of low-carb foods and dietary supplements on blood sugar.

I’m still working my way through whole foods, but it’s going to take a while to get through them all.

In the meantime, I wanted to share my preliminary results and see if anyone has suggestions/requests for what I should include.

If you have any whole foods you like or would like to see tested, please post it in the comments or send me a PM.

Testing Queue:

Whole Foods

For the last several months I’ve been testing the blood glucose impact of tons of different low-carb prepared foods and ingredients. While those tests have been very informative and uncovered a number of surprises (especially around what fibers do/don’t impact my blood glucose), most of what I eat is food I prepare myself using regular meats, vegetables, nuts, and seeds.

Given that I wanted to test the blood glucose impact of regular foods and see how it compares to the macronutrients (total carbs, net carbs, protein, etc.). Towards that end, I’m going to test as many low-carb foods as I can, then see if I can determine any consistent trends.

So far, I’ve tested 15 foods from 4 categories:

The initial results have been pretty interesting. Here are the key insights:

  • All foods tested so far we very low BG impact, so the nutrition labels must be accurate and all of the fibers must be relatively indigestible.
  • The vegetables were the lowest impact per gram, largely due to being such a high percentage water. I was really shocked by how much I could eat (250g mushrooms, 434g celery).
    • If you look at BG impact per calorie, of course, then trend flips around with meat, fish, and nuts having much lower impact than vegetables.
  • I was also pleasantly surprised by how much I could eat of the lowest carb fruits. Raspberries, blackberries, and strawberries were pretty similar to meats on a per gram basis (though not per calorie). I think I’ll start trying adding some in to recipes in small quantities.
  • The zero carb foods (lupini, sacha inchi, salmon, tuna, pork cracklings) still had a noticeable BG impact, presumably coming from the protein content. Once I have more data, I’ll try to fit a model for BG impact as a function of carbs, protein, and fat. It will be interesting to see if there are any interaction effects.

As mentioned above, there’s some many different foods to test, it’s going to take me a while to get a comprehensive set tested. Once I do, I’ll post a full update with a more detail analysis.

In the meantime, since I’ve gotten such great recommendations from the readers, I wanted to solicit suggestions for additional foods to add to this study.

If you have any whole foods you like or would like to see tested, please post it in the comments or send me a PM.

I’ll test all the requests over the next couple weeks and post the results.


– QD

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Low-Carb Flour Replacements: Blood Glucose Testing of 18 Varieties with Some Surprising Results

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This post is an update on my experiments measuring the effect of low-carb foods and dietary supplements on blood sugar.

This week, I have the results from low-carb flour replacements. Next up will be whole foods (meats, vegetables, seeds & nuts, etc.).

Testing Queue:

Flour Replacements

Summary

When making low-carb baked goods, I find that the most difficult ingredient to replace is flour. Flour provides bulk, absorbs water, and binds ingredients together, creating the structure of most baked goods. Unfortunately, flour is ~75% starch by weight with a glycemic index of 70, resulting in an extremely high impact on blood sugar.

Historically, there hasn’t been a lot of low-carb replacements for flour available, mostly almond flour, coconut flour, and resistant starches. Similar to other low-carb products, a ton of new flour replacements have hit the market in the last few years. As always, the net carb counts look good, but I wanted to test them to see if they really hold up (see evidence of blood glucose impact of dietary fibers here & here).

Between my own searching and reader recommendations (1, 2, 3), Foods. I tested 18 flours from 6 different categories (grouped by main ingredient). Here’s my overall conclusions:

  • Most Similar to Wheat Flour: Carbalose
    • <30% BG impact of wheat flour, <20% of white bread
    • texture & water uptake very similar to wheat flour
  • Lowest BG impact: Ground chia seeds
    • 12% of wheat flour, 8% of white bread
  • Best Binders: Gluten, chia seeds, flaxseed, and psyllium husk
    • These work great to tune the texture of other flour replacements
    • Which one is best to use probably depends on the specific recipe/desired texture
  • Best Pre-made Blends: King Arthur Keto Flour & Carbquik
    • King Arthur is a flour substitute, though more elastic/chewy
    • Carbquik is like Bisquik and great for biscuits, pancakes, muffins, and other airy baked goods.

Details

Continue reading “Low-Carb Flour Replacements: Blood Glucose Testing of 18 Varieties with Some Surprising Results” →

Vinegar Study Phase 2 – A Palatable Protocol with the Same Effect as Concentrated Vinegar

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Acknowledgements: Thanks /u/genetastic for advice on the statistical analysis!

This post is an update on my experiments to quantify the effect of vinegar on blood glucose & to better understand the underlying mechanism by determining how this effect varies with person/metabolic status, dose, source of calories, and type of acid.

Previous posts in this series:

Phase 2 – Testing Diluted Vinegar

Summary

In Phase 1, /u/genetastic, /u/kabong, and I replicated the literature showing that vinegar can reduce the blood sugar impact of complex carbohydrates (white bread). From those experiments, we found that:

  • Vinegar significantly lowered blood glucose
    • Peak change in blood glucose & iAuC were reduced by 20% and time to peak blood glucose & initial rise were slowed by 15-20 min. (30-50%).
    • P-values were all <0.05, with the exception of the drop in iAuC, which was 0.12
  • The concentration of vinegar we used was extremely unpleasant to consume. So much so that I, at least, wouldn’t be willing to use it for additional experiments, much less daily life.

In this Phase, I tested a more palatable protocol, vinegar diluted in water (~30g vinegar in ~325g water) drank immediately before the meal. Here’s a summary of the results & next steps (full details below):

  • Diluted vinegar had a statistically significant and meaningful impact on blood glucose compared with no vinagar:
    • Peak change in blood glucose and iAuC were reduced by ~20% and time to peak was slowed by ~20 min.
    • P-value was <0.05 for the change in peak blood glucose, but not for iAuC and time to peak.
  • Diluted vinegar gave very similar results to undiluted, with virtually no change in peak blood glucose and only a modest increase in iAuC and decrease in time to peak. None of these differences were statistically significant.
  • These results give further evidence that the effect of vinegar on blood glucose is real and provide a practical protocol that can be used for further experiments. For the next phase, I will be testing the following:
    • Alternate macronutrients (simple sugars, proteins) to determine scope of the effect
    • Alternate acid sources to test the amylase-inhibition hypothesis
    • Whether this effect is significant with full meals, including insulin doses
      • For this last experiment, I will randomly drink 30g ACV in 325g water before my standard breakfast (50g ketochow, 2 tbsp butter, water to 12 oz total volume) and monitor BG impact.

It would significantly improve the study to have a larger number of participants. If you’re interested in collaborating on this or other scientifically rigorous self-experiments with low-carb foods, supplements, or other health interventions, please let me know in the comments or via the contact form on the right.


– QD

Details

Continue reading “Vinegar Study Phase 2 – A Palatable Protocol with the Same Effect as Concentrated Vinegar” →