Health Experiment: What Sugar Does to Your Body

Freestyle Libre 2 CGM Test Results (Part 1)

9 min readApr 3, 2024

Recently I read in the newspaper that the amount of people that get diagnosed with diabetes increases every year. This is worrisome.

First of all: What is diabetes?

Diabetes is a medical condition where your body is unable to regulate glucose (sugar) levels in your blood.

These sugar levels need to be kept in check. Not too much, not too little, but just right.

If it doesn’t happen, it can have a series of bad effects on our bodies:

Not enough or too much energy: Your body runs on glucose, a type of sugar, which gives you the energy to do everything from breathing to running a marathon. If your sugar levels are too low, you don’t have enough fuel. Too high, and it’s like flooding the engine of your car.
Bad mood and focus: Ever feel grumpy or foggy when you’re really hungry? That’s often because your sugar levels are low.
Dangerous for body & organs: High sugar levels can damage vital parts of your body over time, like your heart, nerves, and eyes.

Summarized, diabetes can seriously affect your long-term Health. Over time, if your sugar levels are often too high, it can lead to serious health problems, like heart conditions, nerve pain, kidney issues, eyesight issues, foot problems, skin and hearing degrading, brain fog, mood shifts… etc.

Oh and have I mentioned that once you have it, you’ll never be cured?

Needless to say, getting diabetes is something you really want to avoid.

What causes Diabetes?

Scientifically speaking, there are 2 types of diabetes. Diabetes Type 1 & Diabetes Type 2. In this article, I’ll only be talking about Type 2.

Diabetes type 2 can have various causes:

Unhealthy food
Not enough physical exercise
Overweight
Too much belly fat (caused by the above 3)
Aging
Genetics
Smoking
Having more than 3 meals per day (yes, shocking right? And with “more meals”, I mean eating constantly snacks).

These days one of the most common causes of getting the disease is a bad & unhealthy lifestyle, which leads to being overweight and having too much belly fat.

This has a few (frustrating) reasons:

Society is promoting crappy food (or at least not doing anything against it). Look at all these cookies & McDonald’s & … ads on TV.
People have gotten more and more lazy
Healthy food is usually more expensive than crappy food
There’s just not enough attention for healthy lifestyles.

And maybe one of the most important reasons:

People think that eating multiple (more than 5) meals per day is good for them.

Yes, it ensures that your digestive system is constantly working (for fat burning)
BUT, because it’s working all the time, chances are that it will get overloaded, overworked, and in time: cease functioning optimally (simply said).

And if it doesn’t work well anymore… it will get hard to regulate your sugar levels.

I bought a Continuous Glucose Meter (CGM)

I am a 34-year-old healthy male, skinny, fit, and never had any health issues. Then why did I buy this thing?

And… what is it?

Simply said — it’s a sensor that measures the blood sugar level (blood glucose), and also displays how the values are evolving, which makes it easy to quickly respond to possible hypoglycemia (blood sugar too low) or hyperglycemia (blood sugar too high).

The delay of the measurement compared to the current blood sugar can be up to 10–15 minutes.

There are various brands available — I bought the FreeStyle Libre 2.

Applying the FreeStyle Libre 2 CGM

Today I got my FreeStyle Libre 2 in the mail. I had been watching YouTube videos about it, so I knew what to expect in the packaging & how to apply it.

After disinfecting, I applied it to the back of my left upper arm. The feeling is a little bit unpleasant, or maybe I’m just a pussy.

Upon applying, there’s a tiny needle that goes into my upper arm, which stays there for 2 weeks. I hate needles, so just the thought of this right now — while typing — makes me shiver. Brrrr. Let’s quickly move on.

How does it work?

After applying the sensor, I first had to wait for around 15–20 minutes, because it first needs to gather some data.

In the mean time, you need to download the FreeStyle LibreLink app.

With this app, you can scan your sensor (via NFC, by hovering over it with your phone) — to read the values. You can also use a reader (device that reads the sensor), but I didn’t purchase that because my phone is good enough.

So in short:

Sensor is placed at the level of the upper arm
Download app
Sensor automatically records the glucose concentration every 15 minutes, for a maximum of 8 hour.
Scan by hovering over the sensor
The data transfer is manual, which means it’s necessary to scan regularly.
You need to scan at least once every 8 hours, otherwise you lose data.

The data transferred displays your blood sugar level (blood glucose); which is the amount of glucose in the blood at a given time. Here’s an example of one of my results:

But what exactly do these results mean?

What are the general “normal” values?

As you can already see on the screenshot above, my values are within the green area — meaning they’re good.

However, there are some spikes and some “crashes”. But is this normal?

I did some research:

Less than 60–70 mg/dl: Hypoglycaemia (too low values)
70–110 mg/dl: Normal. Before eating, after overnight fast.
Less than 180 mg/dl: Max target 2 hours AFTER eating → OK (not great). Ideally it should get back to much lower regions (100–140).
More than 200 mg/dL after two hours: Means you probably have diabetes (because your body is unable to get the glucose levels down automatically, as it should).

So ideally I should always be between 70–140 mg/dL.

I hope I don’t have pre-diabetes

There is also something called “pre-diabetes”.

According to the “Center for Disease Control and Prevention (CDC)”, about 98 million American adults — 1 in 3 — have prediabetes (Source).

Needless to say this is NOT GOOD.

Below you can see a graphic which indicates the Normal — Prediabetes — Diabetes levels and their corresponding values.

Fasting Blood Sugar Test

This measures your blood sugar after an overnight fast (not eating).

A fasting blood sugar level of 99 mg/dL or lower is normal
100 to 125 mg/dL indicates you have prediabetes
126 mg/dL or higher indicates you have diabetes.

Glucose Tolerance Test

This measures your blood sugar before and after you drink a liquid that contains glucose. You’ll fast (not eat) overnight before the test and have your blood drawn to determine your fasting blood sugar level.

Then you’ll drink the liquid and have your blood sugar level checked 1 hour, 2 hours, and possibly 3 hours afterward.

At 2 hours, a blood sugar level of 140 mg/dL or lower is considered normal
140 to 199 mg/dL indicates you have prediabetes
200 mg/dL or higher indicates you have diabetes.

I’m planning to test this by drinking some chocolate milk and eating sugary foods. Won’t be really as representative as the real test, but it will give me some idea at least.

You’re lucky — It’s reversible!

So according to a study — as mentioned above — about 98 million American adults — 1 in 3 — have prediabetes.

However, it seems like you can prevent or delay prediabetes from turning into type 2 diabetes with simple, proven lifestyle changes.

My Expectations?

Before buying this (because it’s still quit expensive — around €66), I made myself a list of things I wanted to check with this tool:

My glucose levels (and hoping that they would be between the expected range)
How my body reacts to different foods I eat (i.e. how high my blood sugar will spike after I for example drink a cup of chocolate milk, in comparison to a salad).
How quickly my blood sugar levels get back to normal
The effects of fasting on my sugar levels

My Tests That I will do

To get the most out of the sensor (it’s only working for 14 days), I made myself a bit of a test-plan of things I want to try out:

Day 1–4: Just normal lifestyle. See how the values are if I don’t do anything special.
Day 5: Fasting for 16–26 hours (fasting is supposed to cause very low sugar during period of no food, and very high sugar when breaking fast). Also depends on what I’ll eat probably.
Day 6–7: Eating more unhealthy, eat sugar foods and record the results.
Day 8–9: Diet, very healthy food. No sugars at all (keto).
Day 10: Fast
Day 11–14: Normal lifestyle.

During these days, I’ll also be doing the following things:

Try different types of training: Cardio, Plyometrics, Core, Running, Insanity…
Try ice baths / cold showers
Try sauna
…

I will record every activity and every meal in Google Sheets:

tracking my activities & results in Google Sheets

Alright, Let’s Start!

So, I applied my sensor on Easter — Sunday 31 March 2024.

This was a day with a lot of chocolate, food & alcohol. The perfect test to see what would happen.

I expect really, really bad results.

I started off with a blood sugar level (glucose level) of 123 mg/dl. According to my app, this is “in range”. Okay.

After applying it, I had some champagne, BBQ food and red wine.

This are the results of my first day:

Based on this let’s check some things:

There’s a spike at 6PM, when I started drinking wine & eating
It went down quickly & nicely after eating → Good
It DID NOT stay within the levels of 70–140 mg/dL (it spiked to 146)

However, this is not that bad.

The size of your spike also depends on the glycaemic index of what you eat.

Glycemic index (GI) is a relative ranking of carbohydrate foods based on their effect on blood glucose levels.

0–55: Low glycaemic index: These products have minimal effect on your blood glucose.
55–70: Average glycaemic index: The impact of these products can be higher, depending on the rest of your meal. It’s about combining the right things.
70–100: high glycaemic index: Foods that are digested quickly and release glucose into the bloodstream rapidly have a high GI value. Be careful for those.

There’s also a thing called Glycaemic Load, but I’ll not dive further into that now.

Source: Glycaemic Index Tables: Check the GI of Popular Foods — Weight Loss Resources

So if I would look at this table, and map it to my “Easter Sunday Meal”:

White Rice has a GI of 70 (high)
Cooked carrots has a GI of 85 (very high)
Chicken has a GI of 0 (protein)
Boiled potato has a GI of 70 (high)

Based on this info, it’s normal that it spiked to 146 mg/dL.

The important thing is that it gets back to normal after max 2 hours!

Conclusion (for now)

I’ve decided to end this article here for now, because otherwise it might get too long.

I’ve only been tracking my glucose levels for 3 days, but I’ve already learned SO MUCH.

For the moment, my levels seem OKAY, but I’ve noticed something worrisome:

My glucose levels in the morning (after sleeping & not eating during the night) — are quite hight.
Some unexpected foods REALLY spike my levels — should I cut them from my diet?

Either way, I can recommend ANYONE to buy a sensor like this, it’s truly eye-opening.

Spoiler alert

At the point of writing this article, my sugar spiked to 160 mg/dL. This worries me a bit.

Do I have pre-diabetes?

I’ll be giving you more updates in the coming days!

Stay Tuned!

Cheers, Michiel

Thanks for reading!

If you’ve got questions or thoughts, drop them in the comments and I’ll get back to you! Follow or 👏 if you’d like to see more content like this. Or buy me a coffee, this stuff is magical ;)