CGM Study Results – Controlled Carb Eating

I have shared two blogs related to the Oral Glucose Tolerance Test (OGTT), The Dreaded Oral Glucose Tolerance Test and Third Time’s A Charm.  I actually looked at my insulin response and my husband’s on the OGTT and once his study is over, I will share what I learned from my now n=2 study and scholarly articles on the subject.

I have shared one Continuous Glucose Monitor (CGM) post so far, CGM Study Results – Low-Carb Eating, which started the story on my day-to-day eating and subsequent glucose response.  That blog was about stability; whereas, this one will be about how my body responds to sugar in a mostly controlled manner.

During my first ten days with the CGM, I experimented with foods containing a varied amount of sugar.  Most of the experiments were controlled (one definitely was not, but it was planned that way), where my baseline sugar was stable and appropriate before eating the sugar.  I also didn’t compound sugar on top of more sugar with two exceptions.  One was the Torchy’s/Ice Cream Experiment; the other was a series of three beers.  Rather than go through the experiments one-by-one, I will continue the takeaways that I began in the previous blog.  There will be a lot of pictures and plots this time, as I want the data to tell the story!

Takeaway #7:  What goes up, must come down – I have a mostly predictable response to sugar when it’s eaten in a controlled fashion.

I introduced some higher carb snacks during my low-carb eating to see what the effect would be on my blood glucose.  I have ranked these in order of carbohydrate amount, which (somewhat) corresponds to increasing spikes in my blood glucose.  For each, I list the amount, where the nutritional information came from, as well as the calories, net carbohydrates (grams of total carbohydrates minus grams of fiber), and amount of sugar.  I also provide the starting glucose, the spike, and the total increase.

Thrive Market plantain chips (28g, label)-150 calories, 15g net carbs, 2g sugar

Glucose change:  86mg/dL to 114mg/dL = increase of 28mg/dL

Major Hazer India Pale Ale 6.5% ABV (16 oz, estimate)-307 calories, 20g net carbs, 0g sugar, 31g alcohol

Glucose change:  97mg/dL to 120mg/dL = increase of 23mg/dL

HEB Thumbprint cookie (1, estimate)-200 calories, 20g net carbs, 9g sugar

Glucose change:  102mg/dL to 162mg/dL = increase of 60mg/dL

Chocolate Covered Strawberries (2 large, website)-300 calories, 28g net carbs, 22g sugar

Glucose change:  84mg/dL to 130mg/dL = increase of 46mg/dL

Oreo Thin Bites, fudge dipped cookies (1.7oz, label)-240 calories, 32g net carbs, 23g sugar

Glucose change:  97mg/dL to 119mg/dL = increase of 22mg/dL

In general, the more carbohydrates the food item had, the higher my glucose response.  The spike generally came between 45-60 minutes after eating the food.  The biggest exception was with the Fudge-Dipped Oreo cookies.  It spiked faster (34 minutes) and didn’t go as high.  There was also a secondary spike that came approximately an hour later.  My theory on why the glucose effect was muted is that I snacked on this day, rather than have three straight meals.  I assumed my glucose (and thus insulin) had returned to baseline, but maybe my pancreas was ready and waiting!

In contrast, the HEB cookie had a larger response than I expected (60mg/dL)!  That was on Day 1 when I took the OGTT and was able to get away with a low carb lunch to achieve stability.  However, I’m not sure I was safely off of the sugar roller-coaster at that time.  My normally low-carb body had to be pretty confused with all of this sugar!  I think I was so excited about the CGM that I tried to cram in too many experiments without giving my body time to completely deal with the 75g of glucose from the OGTT.


Takeaway #8:  Sometimes food you think is low-carb has hidden sugar in it.

ChinaStar-steamed shrimp w vegetables, broth, and chili oil; fortune cookie (alternate website, estimate)-416 calories, 16g net carbs, 6g sugar

Glucose change:  94mg/dL to 135mg/dL = increase of 41mg/dL

This was really surprising to me.  There’s a local Chinese restaurant that has “Diet Dishes”.  The meal is steamed shrimp and vegetables (they customize the vegetables for me).  It’s served with steamed rice that I don’t eat.  It also comes with a “broth” – or so I thought…  Apparently the broth is loaded with carbohydrates and I now know not to add it to my food, or if I do, to only add a little!  Here I thought I was eating low-carb, but the glucose monitor proved otherwise!


Takeaway #9:  During controlled-carb eating, three beers in sequence doesn’t give the blood glucose spike that I expected.


Petrus Sour Blackberry Beer 7.3%ABV (10 ounces, estimate)-104 calories, 11g net carbs, 0g sugar, 22g alcohol

Glucose change:  88mg/dL to 105mg/dL = increase of 17mg/dL

Time=17:13 (with low-carb dinner)

Community Citra Slice India Pale Ale 7% ABV (16 ounces, estimate)-307 calories, 20g net carbs, 0g sugar, 34g alcohol

Glucose change:  87mg/dL to 102mg/dL = increase of 15mg/dL


Petrus Saison de Sour Beer 5.8% ABV (10 ounces, estimate)-104 calories, 11g net carbs, 0g sugar, 22g alcohol

Glucose change:  101mg/dL to 104mg/dL = increase of 3mg/dL

Basically, there was no real glucose response to having three beers in series with a low-carb meal (it was a relatively short time frame, which is why the “dots” in the above pictures are close together).  Previously, I showed that one beer had a moderate effect on my blood glucose, but this did not come close to that.  I don’t have a great answer for why this happened, other than it was on the last day of my 10-days of controlled eating and was several hours after the surprising response from the Chinese food.  Perhaps some beers have higher sugar content than others?  Maybe the low-carb food moderated the beer’s effect?  I really don’t know; I just know that this experiment looked like my normal “low-carb” eating when I drank 36oz of brew!!


Takeaway #10:  My body’s response to sugar is somewhat similar when a high carbohydrate meal is repeated.

MOD Pizza-11” pizza, red sauce, mozzarella cheese, chicken, chicken sausage, bacon, roasted red peppers, serrano peppers, green peppers, broccoli, garlic, 375mL Waterbrook Chardonnay (consumed 1/2, website)-664 calories, 56g net carbs, 3g sugar, 26g alcohol

Day 1 Dinner-Glucose change:  101mg/dL to 156mg/dL = increase of 55mg/dL

Day 6 Lunch-Glucose change:  94mg/dL to 128mg/dL = increase of 34mg/dL


Unfortunately, the first half of the pizza meal was on Day 1 and when my blood glucose wasn’t completely stabilized from the HEB cookie (this was how I learned I needed more time in between experiments), so there is a difference in response, but the elevated glucose levels after the “peak” are consistent in both meals.  On Day 1, crazy things happened overnight (see the next two takeaways below), but that didn’t happen on Day 6.  I believe the larger spike on Day 1 was due to the OGTT and needing an overnight fast to recover from that.


Takeaway #11:  Sugary drinks cause elevated overnight glucose concentrations.

Jose’s Mexican-water, large house margarita, 12 tortilla chips, salsa, two beef fajita tacos (no tortilla), chicken fajita taco (no tortilla) (estimate)-1488 calories, 87g net carbs, 41g sugar, 36g alcohol (most of the carbs are from the margarita)

Glucose change:  94mg/dL to 142mg/dL = increase of 48mg/dL

This seems like a normal response for a large sugary margarita and a few chips (otherwise, everything was low-carb), however, my glucose levels hovered between 102-117mg/dL until almost 8am the next morning!  They were relatively constant, just high!  In contrast, Day 1’s overnight was a little more varied and crazy.  I was still on the sugar roller-coaster while I slept.  It appears that my blood glucose stabilized after dinner, but once I was happily sleeping, it went absolutely crazy.  Remember this pattern… you’ll see more of it!

Crazy Overnight


Takeaway #12:  The cascade effect of carb on carb loading is long-lasting.

Here’s the “Torchy’s/Ice Cream Experiment” – a well-established problem area for me.  I previously called my efforts to understand it “Sugar Experiment” and “Alcohol Experiment,” but I figured I should be more descriptive.  I think I was just afraid to implicate Torchy’s as being responsible… when it’s just my crazy body!

You can read the backstory in:  What Leading By Example Is Not…Houston, We Have a ProblemSugar Experiment #1, and Alcohol Experiment #1.

The goal of the experiment was to eat my favorite Torchy’s meal, which involves margarita martinis (no sweet and sour), chips and queso, and the same low-carb tacos that I have shown behave well with the CGM.  However, experience has taught me that this combination of food and alcohol encourages the consumption of ice-cream, and that makes everything go crazy, as described in those blogs.


Torchy’s-Two Torchy’s Tini’s (made with lime juice, no sweet and sour), chips and queso with chorizo, brushfire bowl (no sour cream, add grilled shrimp), beef fajita bowl (website, estimate)-1377 calories, 75g net carbs, 31g sugar, 36g alcohol

Glucose change:  96mg/dL to 130mg/dL = increase of 34mg/dL

Okay, that’s pretty reasonable… and my blood glucose was on the way down before that next “dot” where I decided to compound the effect.


Freddy’s-Regular PB&C Concrete (website)-980 calories, 113g net carbs, 93g sugar

Glucose change:  96mg/dL (same as above) to 164mg/dL = increase of 68mg/dL

Now things are starting to get a little crazy…. but, what happened overnight?

Similar to the sugary margarita and and OGTT, my glucose concentrations took until the next morning to stabilize and in this case were insanely high overnight!  Additionally, my blood glucose was still elevated until after my low-carb breakfast the next morning.  As expected, I felt horrible all night (same symptoms are recorded in the previous blogs regarding this phenomenon), as my body worked to rid itself of the crazy levels of sugar that I had forced upon it.  I was excited to finally have a picture of what happens to my blood sugar during the Torchy’s/Ice Cream Experiment!!

The data presented here and in my previous blog are from my first ten-days wearing the CGM devices.  All of my non-low carb meal choices are presented in one of the takeaways;  all other meals during the 10-day period were low-carb and all other blood glucose plots (including the overnight data) were uneventful.  I was mostly able to establish a stable blood glucose level before embarking on another experiment.  I also had a relatively stable weight during the ten-day period, with a net weight loss of one pound, as measured on Day 10 relative to Day 1.

My next blog will cover the final takeaway in additional detail and will focus on the second ten-day period, where I allowed the Standard American Diet to completely take over.   Stay tuned!!



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