Last Updated 1 year by Lukas
We are blessed to live in amazing times. We have many opportunities what to do, what to discover, what to explore. One of the very interesting areas of human creation is modern gadgets, from IoT devices to robotic vacuum cleaners to health monitoring wearables. In this article, let’s explore together what a CGM sensor is and how we can use it to our advantage.
What is CGM sensor?
Continuous glucose monitoring sensors are modern tools that allow us to continuously check the glucose levels in our blood. They’re small, wearable sensors that usually last between 10 and 14 days before they need to be replaced. These devices can give us insight into how our body manages glucose levels throughout the day.
The sensor is painless to use because it has a very short needle that goes just under the skin. This means that the sensor does not actually measure glucose levels in the blood itself, but in the so-called intercellular fluid. Otherwise, the measurement would be delayed by about 10 minutes. The glucose level first rises in our blood and then it’s transferred to the intercellular fluid where the sensor can measure it.
If we compare this approach with the invasive method that is currently widely used, where you have to take a little drop of blood from your finger and put it into a glucose meter. It’s definitely much more convenient and it allows continuous monitoring, which gives you trends over time. You simply download the data to your phone via NFC and then you can even share it with your doctor via cloud services.
Currently, we can find two CGM sensors on the Czech market. One is Dexcom G6/G7 and the other is FreeStyle Libre 1 and 2. I have personal experience with FreeStyle Libre 1 and 2, which are freely available in e-shops or pharmacies. Of course, in the case of a healthy person, it has to be fully self-funded, but it’s very reasonably priced considering what it provides.
Why should we consider using it?
Unfortunately, the more convenience we bring into our lives through technology and the faster our lives become, the less time and energy we have to do what is really important for our bodies to stay healthy. Our bodies were designed to move and our current sedentary lifestyle is not helping us to live longer.
High blood sugar levels, like high blood pressure, are silent killers. They can go unnoticed for years, during which time they can cause irreversible damage to our bodies. Or, of course, our bodies are amazing and can compensate for much of this damage for years to come, but do we really want to destroy them? Because one day we will have to pay back the loan to our body. And by that time it will be too late to complain that the quality of our lives is worse than we would like it to be.
FreeStyle Libre 2
Introduction
It’s a coin-sized CGM round sensor. We can buy it at the pharmacy. It’s currently fully covered by insurance companies for people with diabetes. It is painless to apply and sticks to the skin with glue. For people who like sports, it is recommended to use extra patches (stickers over the sensor) to protect the sensor adhesive. The sensor can be used for 14 days and supports NFC to read values and Bluetooth to send low/high glucose alerts to your phone.
Connectivity and Software
Sensor supports NFC to read values from it. It can store up to 8 hours of glucose readings internally. This means that you need to scan it at least every 8 hours if you want to keep all your readings. It also has built-in Bluetooth, which can connect to your phone and send alerts if it detects high or low glucose levels. These conditions can be dangerous and it’s important to at least be aware of them.
The application is able to show many interesting graphs, averages, calculated values or daily trends with probabilities where your glucose is most likely to be based on historical data. There is also a cloud version available from your browser and a special application for your GP. You can easily share your readings with others or, in the case of children, with their parents.
Precision
The accuracy of CGM sensors is measured using a metric called MARD (Mean Absolute Relative Difference). FreeStyle Libre 2 has a MARD of around 9.3% (lower is usually considered better) over it’s 14 day lifetime. There is a newer iteration of the sensor called FreeStyle Libre 3 (not yet available in the Czech Republic) and this reported a MARD of 7.9%, making it the first CGM with a value below 8%. The sensor itself reads every minute, but in the case of the Libre 2, it’s later grouped into 15-minute intervals and transferred to the phone via NFC.
Conclusion
When used by people with diabetes, it can improve control and monitoring of glucose levels. This is very important as high/low glucose levels can have very negative effects on our bodies. This sensor can also be used by healthy people who are interested in prevention (as high glucose levels can go unnoticed for long periods of time) or who are simply interested in knowing how their body reacts to different foods. With this knowledge and by recording how we feel, we can improve our behaviour and improve/maintain our health in the future.
Personal experience based on 14 days use
As I’ve been using the sensor for 14 days, I’ve tried different approaches to eating in a restricted window, exercising, walking or just keeping a diary of what I’ve eaten. I’d like to share my personal experience along with my daily routine as it’s an important piece of the puzzle. Of course, for others it is just a direction. In your specific case, your body may react differently and your daily routine may also play an important role.
My Daily routine (working days)
- Get up at 5:30
- Exposure to strong (1000 W) red light. Exposure to daylight outside if possible.
- Cold shower (about 2 minutes to fully wake up)
- Lying on the ‘Kuznecov’s pad’ (pad with many needles) + breathing excercise (around 5 minutes)
- Between 6:00 – 8:00 (possibly until 9:00) – reading, writting, exercising (jogging outside, elliptical at home, push-ups, pull-ups …)
- At 8:00/9:00 start work + walk on the treadmill (3,5 – 7,5 km/h). Try to do at least 10k steps every day
- Eat between 12 – 20 (try to finish any major meal until 18:00. During the fasting period I only drink water, plain coffee or plain black tea)
- Try to finish work by 17:00 (If possible)
- Going to bed within the 21 – 23 window (Most common time is around 22)
Conclusions based on sensor use
- When you wake up, there is a slight (short-term) rise in blood sugar. I think this is because your body is preparing for the day. The spike is there even if you fasted from 6pm the day before.
- It is very important what you eat, when you eat and if you exercise in between.
- If you have a meal and then do some light exercise such as slow walking. This helps a lot to keep sugar at the expected level. This is because your muscles will start using it from the blood to rebuild energy reserves.
- Shortly after a meal, your blood sugar can drop below the accepted lower limit of 3.9 mmol/l, and that’s because your body has released insulin and your cells are using blood sugar. This leads to a sudden drop. In a healthy body, it’s regulated back to normal levels within a few minutes. Of course, combining this with exercise can increase this effect. In my case, I felt fine at 3.5 mmol/l.
- If you do a lot of exercise during the day and fast for up to 24 hours. I was able to measure 3.0 mmol/l around midnight. I felt very good and calm again. In the morning I was back within the normal range of 3.9 – 5.9 mmol/l.
- It’s advisable to eat at least 2 hours (ideally 4 hours) before going to bed (better to eat a small portion in the evening). If I ate a lot after 8 pm and went to bed shortly afterwards. My blood sugar fluctuated between 6 – 7.5 mmol/l during sleep. This was definitely not good + it ends up as stored fat.
- General rules (based on my personal experiments):
- Exercise as simple as walking can help regulate blood sugar levels (as muscles take sugar from the blood).
- Sugar levels slightly below the generally accepted 3.9 mmol/l in a healthy person are normal. (A level of 2.2 mmol/l is life-threatening! If you fall below 3.0, please consult your doctor!)
- Eating large portions late at night, just before going to bed. This is definitely not a good idea. It will disrupt your sleep, create extra fat and keep your blood sugar levels high.