4 lessons a non-diabetic learned from wearing a CGM
If you have spent any time at all in the “health and wellness” public sphere, listened to any podcasts, or read any articles dedicated to that topic, there is a good chance that you already know, what a CGM is, but let me reiterate.
What is a CGM?
CGM is an abbreviation for a continuous glucose monitor — a device measuring the concentration of sugar between the users’ fat cells (usually on the back of an arm). Based on that measurement, the machine provides its user with a fairly good estimation of their blood sugar level. Unlike traditional glucose monitors, a CGM sends real-time information without the user having to draw blood by piercing their skin multiple times a day. Once installed, it can usually last for 7 to 14 days and most of them can be paired with a smartphone to display the data.
Originally, glucose monitors were developed for people, who suffered from diabetes. Lately, however, they have become more popular among healthy folks, who are interested in how their bodies work and what they can do to persist or improve their well-being. That was, at least, my interest in getting one.
Why even bother?
From the “Glucose Revolution” book by Jessie Inschaupe, as well as from some other sources, I learned a bunch about glucose spikes — the unhealthy phenomenon, that can happen to non-diabetic individuals, cause all sorts of short-term side-effects as well as generate long-term low-grade inflammation in the body. For years I have been suffering from sinusitis, so I wondered, whether a CGM could help me find the reason for that.
I started out with one glucose sensor and after two weeks decided to purchase another one, as I was interested in experimenting for a longer time. I live in Denmark, where a healthy individual can not buy a CGM at a pharmacy without a prescription, so I bought them online from private people.
Here are the most important lessons I learned from this month-long experiment:
Lesson 1: Breakfast really IS the most important meal of the day — but not in the same way you think it is
We all heard from our parents, television, and health experts about the importance of having a hearty breakfast. Apparently, this belief became popularised by cereal and bacon lobbyists in the 19th century. Today we know, that some people can be perfectly healthy without eating in the morning, but as a society, we still stick to the concept of breakfast. Moreover, while I do not have proof of this claim other than anecdotal data, seemingly plenty of people prefer to start their day sweet, rather than savory.
Interestingly, from the book “Glucose Revolution” I learned that having the first meal of the day sweet can have a negative effect on the rest of the day. Not only it can cause a big glucose spike, but it also makes the body vulnerable to more volatile glucose ups and lows from the following meals.
Well okay, not sweet then — I thought to myself, preparing my favorite morning food, a pack of smoked salmon and half a baguette with garlic butter. That’s not sweet, so it must be glucose-safe, right?
Unfortunately, I was wrong. Consuming that huge half-a-loaf of white bread caused a huge spike in return and a dramatic drop in my blood sugar, which made me tired and sleepy. This was such an “aha” moment! Prior, I had spent months trying to solve the mystery of my randomly occurring fatigue, by adding supplements like iron and magnesium to my diet to no success. The answer to it was — bread.
My further experiments showed, that the foods that cause the most stable reaction in my blood were eggs, fish, meat, and non-starchy vegetables. Just a few bits of dark rye bread caused a spike, even when the amount of it was much smaller than that delicious baguette According to my CGM, having fruit during or right after breakfast also turned out to be a bad idea.
Now I usually start my day with a hearty “sandwich”, still with salmon, but with avocado instead of butter, a bunch of leafy greens on top, and on a 2-egg-omelet instead of bread. My glucose? Stable like never before.
Lesson 2: Sushi is not that healthy
Did you also expect sushi to be one of the healthier food options? Because I for sure did. I told myself “Fish, lots of protein and healthy fats? that must do wonders for my body!” And while fish, algae, and vegetables are all good options, unfortunately, they are usually surrounded by a blend of white rice with sugar.
Typical sushi recipes, besides sugar call also for vinegar and other flavor modifiers, so we usually do not taste the sweetness. However, not only is white rice a simple carb, which can already be problematic alone, but its combination with sugar gave me the biggest spike I have ever seen on my CGM reading.
That was also when I discovered, what “glucose hungover” was. The next day after my delicious sushi dinner, I felt incredibly sluggish, despite having had a coffee, regular exercise, and many nights of sufficient sleep. I was not able to explain this fatigue and the hungover-esque feeling by anything else, but the takeaway I had enjoyed the evening prior.
I still believe, there are healthy ways to enjoy sushi. I swapped my soya sauce for tamari (a gluten-free, hence lower-carb version of a standard soya sauce), and I now choose options like sashimi or bowls with veggies in fish while skipping the rice.
Lesson 3: Fruit can be a problem or a helping line
I am not here to tell you that fruit is unhealthy. But fruit IS a source of sugar, and whether it is natural or not — that is beyond the point. In fact, if you think about it, the source of the table sugar is technically also natural — sugar cane, beetroot, etc.
However, as I mentioned eating a little bit of fruit for breakfast, even after having a savory dish, gave me somewhat of a spike. Generally, eating fruit just by itself, gave me spikes. There was one exception to the rule though.
The thing is, I love to train. Three days a week I spend ~1hr lifting weights at the gym and then bike home for 30 minutes. Sometimes I like to add 10 minutes of interval training after the weightlifting session, and before biking home.
During the month of my CGM experiments, I realized, that when I did the interval training, by the time I would bike back home, my CGM was “in the red” — meaning, my blood glucose dramatically dropped. I was obviously not interested in losing muscle mass, so I started adding a little sweet treat after the intervals.
I am not talking about anything big — rather an apple or another fruit. Muesli bars for example, already gave me too big of a spike. Thus, I discovered, that there is a place and time for fruit — in my case, in the middle of continuous exercise, right after a high-intense effort, before finishing it with a low-effort bike ride. And honestly, I am not sure why, but that fruit tasted much better after some time spent at the gym.
Lesson 4: Potatoes are okay — in the right order and amount
I really like potatoes. Then again, who does not? I was then happy to discover that having a few small roasted spuds for my dinner did not give me a spike, assuming the food was eaten in the right order. The next day, feeling confident about my new potato discovery, I served myself a hearty bowl of soup for lunch, and oops — there it was, a spike! Both soup for lunch, and that dinner with roasted potatoes contained meat and other vegetables, what was different then?
According to Jessie Inschaupe’s “Glucose Revolution”, to avoid glucose spikes, the food should be eaten in the following order: non-starchy vegetables first, then fats and proteins, and then other sources of carbohydrates. I generally agree with that however personal experiments showed me also, that the proportion of the meal components plays a crucial role in glucose processing. My soup, just like a bowl of oatmeal, “spiked” me because the ingredients were predominantly carbs. The chicken-schnitzel dinner with only a few small spuds, or a bowl of Greek yogurt with nuts, topped with a spoon of oats did not cause a spike.
Improved mood and energy levels but not the sinusitis
In the end, going lighter on carbohydrates made me less moody, stabilized my energy, and helped me see my belly flatten a bit. It did not, however, fix my sinusitis, as I had hoped for, at least not after that one month.
I still consider this experiment as valuable, as I learned, that while some of those generic “lifehacks” to avoid glucose spikes (such as eating veggies first, working out after a sweet treat, etc) work on me as intended, others seem to be either more important (avoiding bread or rice) or completely neutral (drinking vinegar before meals did not to do anything at all).
