What I Learned From Wearing a Continuous Glucose Monitor (CGM) for a Month

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I’ve learned over and over that health and wellness is increasingly personalized! I largely credit my transformation to addressing trauma… and figuring out the personalized diet/lifestyle approach that worked for me after years of experimenting.

The latest in my quest for personalized health is wearing a continuous glucose monitor.

As a population, we consume over 10x more sugar per day than we did 100 years ago, so glucose is becoming a bigger and bigger deal.

We All Have to Figure It Out…

Many in the health world have figured out systems and approaches that have worked for them, and while I think we can learn from all of these, we are each responsible for finding what works best for us individually.

We are each our primary healthcare provider, and long term health comes from experimentation and personalization. That’s why I’m such a big fan of data!

Why a Continuous Glucose Monitor (CGM)?

Through experimentation and food sensitivity testing, I have a good grasp of what foods my body prefers and what I need to eat to feel my best. When I get enough protein, avoid eggs (my one remaining sensitivity), and don’t eat after dark, I tend to feel better.

I knew my fasting glucose levels from using an at-home finger stick meter and occasionally also tested my post-meal glucose, but was excited to get more detailed data.

A continuous glucose monitor attaches to the back of the arm with a small filament going into the arm (no pain!). A user wears the monitor for two weeks without removing it and has a continuous window into blood glucose during this time. The monitor and app I used (more on this below) also lets you input food intake, workouts, and other notes to see trends and learn from the data.

Why Does Glucose Matter?

We know that what we eat directly affects blood glucose levels, but the response to specific foods can vary from person to person. Stress, sleep, illness, exercise, and other factors can also make a big difference.

As much as 88% of the U.S. population has at least one marker of metabolic dysfunction, according to recent research. Metabolic dysfunction is connected to or underlies almost all chronic diseases, so this is a big deal!

We know some broad generalities when it comes to blood glucose:

  • No one needs large amounts of refined sugars and carbs, and over time, these seem to impair regular insulin and glucose levels.
  • Not getting enough sleep impacts blood glucose in most people.
  • Stress and illness can change the glucose response.

Beyond these basic glucose “facts,” there is a lot of personalization involved.

For instance, many people benefit from eating some amount of carbs, but the amount and type can vary drastically from person to person. As I’ve reached a healthy weight and am working out more, I need to consume some carbs to feel my best.

The continuous glucose monitor helped me pinpoint the carbs that seemed to work best for my body and fuel recovery best.

Finding My Glucose Equation

Drastically simplified, here’s how glucose works…

Carbohydrates break down into the simple sugar glucose in the bloodstream. When glucose enters our blood, the pancreas releases insulin, which signals cells to absorb glucose. If we need energy, our mitochondria use it to form ATP (cellular energy).

If we consume more glucose than we need, the body stores the extra in the muscles and liver as glycogen or can convert it to triglycerides and store it in fat cells.

But here’s what happens:

When the body has to handle too much glucose over time, it overproduces insulin and becomes insulin resistant over time. Glucose then has a more challenging time getting into cells, so blood glucose stays higher. When insulin is high, the body doesn’t use stored fat as energy. Excess glucose in the blood can also lead to inflammation and oxidative stress.

In short, glucose isn’t harmful. It’s fuel. But too much can be a bad thing, and big spikes can be damaging and lead to oxidative stress.

Since glucose response varies by person, wearing a monitor helped me pinpoint my glucose equation.

What Are Good Glucose Patterns?

Glucose response is one area where “normal” doesn’t necessarily mean optimal. Standard measures consider fasting glucose below 100 mg/dl and 140 mg/dl two hours after eating to be a healthy range and anything above that pre-diabetic or diabetic.

According to Dr. Casey Means, optimal metabolic fitness includes:

  • Fasting glucose between 72-85 mg/dl (mine averages 74)
  • Post-meal spikes that don’t exceed 110 mg/dl
  • Average glucose of 100 mg/dl each day
  • A minimal rise in glucose after eating
  • Quick return to baseline after eating

How I Tested With a Continuous Glucose Monitor

I used the continuous glucose monitor from Levels Health (you can get one here).

I was so excited to see the data and wanted to use the monitor as a chance to test a wide variety of foods. The first week, I consumed foods I’d normally eat and, as expected, had relatively stable glucose levels.

The next week, I decided to experiment a lot and consumed a lot more carbs than I usually would from various sources to monitor my response. Confession: one meal included a whole bag of Siete chips, and my body handles a pint of organic ice cream pretty well *ahem*…

I also used the monitor as a chance to watch my glucose levels respond to a 5-day water fast and was somewhat surprised how low my levels got overnight. (Please talk to your doctor before trying a water fast.)

After four weeks of wearing a continuous glucose monitor, these are some of the things I’ve learned…

What I Learned from My Continous Glucose Monitor

Wearing a monitor confirmed some things I expected, like that refined sugar or processed carbs cause a pretty quick glucose spike. But I found out some exciting things I wouldn’t have otherwise known. For instance, I can eat two sweet potatoes with almost no glucose spike, but one small white potato or a handful of grapes will spike my glucose!

These are some of my crucial takeaways and how they’ve led to lifestyle changes:

Not All Carbs Are Equal

Ironically, my glucose experiment has led to me consuming MORE carbs than I was before. I am careful to get enough protein, which often leads to satiety, so I don’t typically eat many carbs.

The monitor helped me realize that I needed more carbs, especially on workout days, to keep energy levels up. I was able to experiment with a variety of carbs and found that my body did well with:

  • Sweet potatoes
  • Cassava (including cassava chips and baked goods)
  • Berries
  • Apples
  • Most winter squashes
  • Lentils
  • Berries
  • Lemons and limes
  • Organic potato chips in avocado oil

But didn’t handle these as well:

  • White potatoes
  • Grapes
  • Rice
  • Foods with white flour (sprouted flour and sourdough were fine, though)
  • Oats
  • Most dried fruits

Like I said, individual response varies. I’ve talked to people who saw spikes from sweet potatoes but not rice and berries but not grapes. Data helps!

My Takeaway: I kept a log and now have about ten moderate-carb meals that I can consume without a big glucose spike. These are my go-to meals when I need to replenish after workouts.

Protein Gives a Lot More Leeway

I am already careful to consume enough protein because this helped me lose weight, and I know I feel better when I do. It was interesting to watch the effect of protein consumption on blood glucose.

Eating carbs before protein seemed to lead to higher spikes than eating the same foods, but eating the protein first. Eating at least 30 grams of protein per meal kept glucose in a healthier range on average.

I also found that eating enough protein early in the day helped keep glucose in a good range throughout the day and the next morning. As Levels explains:

In one study, consumption of 23 grams of protein and 17 grams of fat 25-30 minutes before carbohydrate ingestion significantly decreased post-meal glucose elevation in nondiabetic individuals and those with insulin resistance.

My Takeaway: This reinforced that I need at least 30 grams of protein per meal and at least 100 grams per day. I now get more protein early in the day at the first meal I consume and eat protein with any carbs.

Sleep Matters As Much As Food

We know that even just a few nights of impaired sleep can cause an otherwise healthy person to have diabetic or pre-diabetic glucose levels. (Yikes for early motherhood).

Restricting sleep to 4 hours per night for just five days has significantly decreased glycemic control and metabolic fitness. In one study, this amount of sleep deprivation led to a higher glucose response to specific foods and a 40% lower rate of glucose clearance from the blood during a glucose tolerance test.

I saw this play out on my continuous glucose monitor too! On days I got 8+ hours of sleep, my glucose would rise less from the same foods than it did on days when I got less sleep. On days after less sleep, I wouldn’t respond as well even to foods that I’d previously handled well.

My Takeaway: Getting to bed before 10 pm and getting longer, better sleep made a measurable difference in glucose response. In other words: more sleep = more carbs without the glucose spike!

Time-Restricted Eating Helps a Lot (Stop Eating After Dark)

Time-restricted eating (TRE) and intermittent fasting (IF) are both methods of eating in a shorter window. I was already a fan of this approach based on my own experimentation and on the work of researchers like Dr. Rhonda Patrick.

As expected, these had an impact on blood glucose. Studies show that the effect can be rapid and pretty drastic:

One study in overweight, non-diabetic individuals showed that even engaging in time restricted feeding for just 4 days can lower fasting glucose, fasting insulin, and mean glucose levels significantly.

and from Levels health:

Intermittent fasting means restricting food intake for longer periods, usually for 24 hours or more. A recent small case report in three individuals with type 2 diabetes showed intermittent fasting could meaningfully reverse diabetes in as little as seven months. These participants did 24-hour fasts, 3-4 times per week.

My Takeaway: I do well with TRE, but my glucose levels are even better if I eat earlier in the day and stop eating earlier in the evening. I eat in an 8-hour window and now eat my biggest meals earlier in the day. Typically, I don’t consume calories after dark, but I drink black coffee and herbal teas outside of this window.

When and How to Hydrate

We all know we have to stay hydrated. We’ve seen the pictures of how just two weeks of proper hydration can impact the skin and make someone look much younger. Water is important, but I learned that timing is essential!

Specifically, I found that:

  • Drinking 3-4 liters of water a day helped with sleep and keeping glucose in a tighter range
  • My body likes drinking lemon water to hydrate in the morning and waiting at least 30-60 minutes to eat after
  • Drinking at meals led to a less favorable glucose response, and I did better focusing on hydrating between meals (this is also good for stomach acid)

My Takeaways: I am more conscious of hydrating now. Typically, I drink a quart of lemon water each morning when I wake up, another quart between each meal, and more if I exercise or sauna.

Sauna and Exercise Impact Glucose

We already know that exercise is essential for many aspects of health, including glucose control and metabolic fitness. It was fun to watch this play out in real-time on the monitor! Just like with food, exercise response is probably somewhat personalized, but research has consistently shown a cause and effect relationship.

  • One study found that only one session of exercise significantly increased insulin sensitivity (which is good) the next day.
  • Many studies have consistently shown that regular exercise improves glycemic control and reduces fasting glucose over time.
  • Even short bursts of high-intensity training improved glucose in diabetics and non-diabetics.

It did surprise me to see relatively big glucose spikes from high-intensity exercise and sauna use. In researching this, I found that not only is this response normal, it’s also beneficial.

Here’s why:

High-intensity exercise and sauna (as an exercise mimetic) require fuel (glycogen), which comes from glucose in the blood and then from stores in muscles and liver.

When we do those activities, the body mobilizes these stores to fuel us, which results in a temporary rise. Over the 24 hours after these activities, the body replenishes these stores by sucking sugar out of the bloodstream and leading to lower and steadier blood glucose overall.

From my understanding, this is why both sauna and exercise lower blood glucose over the long term, but why there can be a short spike that would only be noticeable when continually tracking like this. It’s also why even when I eat a LOT of carbs post intense workout; my blood sugar doesn’t rise much.

My Takeaway: I already knew exercise and sauna were beneficial, but now have more data to see their benefit over time. I also notice that I have a better response from high-intensity sprints and lifting weights than extended cardio, but benefit from walking after meals.

Fasting Sweet Spot

My body seems to like time restricted eating in an eight(ish) hour window most days, but I also wanted to experiment with a longer fast to see what my glucose did.

I did one five-day fast while wearing the monitor, and my glucose was pretty stable for the first three days. After that, it started getting pretty low at night. My ketones also rose at that point, so I ended the fast right before the full five-day mark based on my glucose and how I felt.

I do not think fasting is beneficial or helpful for everyone, but it has been a useful tool for me, and this provided some extra data that will help with future fasts.

My Takeaway: I do great with daily TRE and with fasts up to 3-4 days but my body doesn’t seem to like longer ones right now.

I Do Better with Lower Saturated Fat Intake

This is another very personalized part of nutrition, but I seem to do better when limiting saturated fat intake. I already knew this from a genetic standpoint, thanks to my Nutrition Genome test, but the continuous glucose monitor indicated the same thing.

Studies have shown that consuming too much saturated fat can lower insulin sensitivity, though the amount seems to vary by person. I noticed that my glucose levels were not as good after meals with high saturated fat content and, like I mentioned above, were great with protein and monounsaturated fats.

My Takeaway: I do best when I limit my saturated fat intake to 15-20% or less of my total fat intake.

Supplements Can Help

Many supplements claim to help maintain optimal blood glucose levels. But do they? I used the continuous glucose monitor to test my response to several of them.

Specifically, I tested Ceylon cinnamon, berberine, and Kion Lean. I saw the most benefit from adding cinnamon in the morning (usually in my coffee), taking berberine with meals, and taking Kion Lean at lunch (though this one seemed most cumulative).

My Takeaways: I now take BerbElite with higher carb meals to help my body handle it. You can find links to this and the other products I mentioned below.

Continuous Glucose Monitors: Bottom Line

Continuous monitoring was a fascinating experiment, and I’m so glad I got the chance to see this data in real-time. Since diet is so individualized, I think this can be a valuable tool, especially for those trying to work through blood sugar issues or those who have diet dialed in and want to improve things even more.

Of course this is just what worked for me, but I’m sharing in the hopes it gives you a sense of ownership in your own health journey. I always recommend that you work with a doctor (as I do) to find the right approach for you!

Resources Mentioned:

Levels Continuous Blood Glucose Monitor
Regular Glucose Monitor and Strips on Amazon
BerbElite Supplement
Kion Flex
Ceylon Cinnamon Powder

This article was medically reviewed by Dr. Lauren Jefferis, board certified in Internal Medicine and Pediatrics. As always, this is not personal medical advice and we recommend that you talk with your doctor or work with a doctor at SteadyMD.

Have you ever monitored your glucose? What did you learn?

Katie Wells Avatar

About Katie Wells

Katie Wells, CTNC, MCHC, Founder of Wellness Mama and Co-founder of Wellnesse, has a background in research, journalism, and nutrition. As a mom of six, she turned to research and took health into her own hands to find answers to her health problems. WellnessMama.com is the culmination of her thousands of hours of research and all posts are medically reviewed and verified by the Wellness Mama research team. Katie is also the author of the bestselling books The Wellness Mama Cookbook and The Wellness Mama 5-Step Lifestyle Detox.


7 responses to “What I Learned From Wearing a Continuous Glucose Monitor (CGM) for a Month”

  1. Morgana Avatar

    This was very helpful and timely. I am overweight and menopausal, and have struggled to lose weight. I am not diabetic at this point, but have been insulin resistant for about 20 years. My eating is spot-on, and I have the stress, sleep, food tolerances, exercise, and supplements in check, but found I was still struggling to lose weight. I just started monitoring with a Dexcom G6 this week. I’m finding I have to calibrate it with a BGM every morning, but I’m getting really good Data. Like you, I like data and feel it helps me make informed choices. My BG stays very stable, but seems a bit high most of the time. Surprisingly high after drinking black coffee each morning. I also IF, and have done longer fasts. My doc, a functional med practitioner, says fasting can also cause slightly elevated sugars as people who have been long-term keto, VLC, and IFers can have what’s called “physiological insulin resistance”, meaning their body is being signalled to make glycogen in the fasted state in an environment of low insulin, which is exactly what its supposed to do. I do notiece my sugars go down after eating, as if my body is finally releasing insulin in response to food. I’m still parsing all of this, but appreciate your spirit of self-experimentation. Wearing the monitor for the last couple of days has increased my vigilance and stress a bit, but as I learn more and know what to expect from my body it is also empowering. Thanks again-

  2. Caroline Avatar

    I’ve been testing my blood glucose with a meter (can’t afford a CGM) and found it’s fairly stable. BUT I’m about 50 lbs overweight, so I think I’m insulin resistant and I’m in that in-between stage where my body is controlling my blood glucose well, but probably releases too much insulin to do it. My BG is actually lower for pretty much every food compared to my thin (not skinny fat – his body fat is low) husband! I’m interested in learning how you gathered your data. Did you basically use an elimination diet to test from? You said you’ve experimented a lot with what your body prefers, and then added glucose monitoring in after. I’m thinking a base of beef might work for me, as I feel pretty good on animal fat and protein. With food, sleep, supplements, exercise all having varying effects, I imagine it will take quite a bit of time to isolate reactions to each thing. If you have any tips to share about data collection, that would be great!

  3. Jennifer Avatar

    I have been following your website for years. Always appreciate the informative articles you write. They are always pertinent to so many of the challenges we deal with. I’m so grateful for your success over the years. One observation… coming from a single income, homeschooling mother of four… I’ve found that much of the information and suggested resources you now recommend far exceed financial feasibility for our family. It’s been so disappointing. I read eagerly each article and look up the recommended testing or website suggested only to find it’s hundreds of dollars or even more. I’m sure you get to try these things at no expense and that is great for you! But it’s incredibly disappointing for us when we can’t afford it. Would appreciate more down to earth, financially feasible ideas like you used to give. Thanks for all your hard work researching!

    1. Katie Wells Avatar

      Hi Jennifer, thanks for your feedback. I have a policy of purchasing every item before I recommend it so that I can give an honest and unbiased review. Everyone is in a different place financially, and it’s unfortunate that the best quality is often more expensive. In most of my articles I try to give a 3 tiered approach to products, ie. good, better, best, or low, medium, high, in terms of quality or cost. This is the only continuous glucose monitor I’ve tried, so I can’t recommend any others yet without trying it. I hope that is helpful to you…

    2. Daniela Avatar

      Jennifer, I know exactly how you feel. It is so easy to feel defeated looking at the prices of the latest health promoting devices, supplements or you name it.I try to remind myself that after all the foundations of good health are- good quality food, sleep, sun in the right amounts and staying active. This is where I try to focus our family budget and everything else is a nice bonus if possible. There is so much we can do even on a budget. Wish you and your family lots of health and a happy holiday season.

  4. Lisa Avatar

    Thank you for all the helpful insights. I’ve been wanting to experiment with this and you’ve summed up the range of data in a meaningful way. Also, for anyone considering trying your products, I have tried the toothpaste and it is my favorite. I’ve tried several others (two of those are heavily advertised on Instagram) and I definitely prefer Wellnesse toothpaste. Thanks!

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