You’ve probably seen him wearing a small device on his upper arm in many photos on this website. That’s my continuous glucose monitor (CGM) and a tool that helps me with my daily diabetes management.
It’s a great device and I absolutely love it (mostly).
What is CGM?
The CGM device allows you to view glucose measurements (almost) in real time and track historical glucose data.
Most CGMs contain three main components:
- A small sensor inserted just below the skin (reading glucose levels in interstitial fluids, or fluids between somatic cells)
- The attached transmitter (this is what appears on my arm) sends the measurements to the receiving device
- Receiver or smartphone to display measurements and glucose trend data
Currently, there are several CGM systems that you can use personally in the US.
My experience with CGM
I got my first Medtronic CGM in December 2012 and wore it every day for 18 months before taking a break. I then ordered my first Dexcom system in August 2016.
Every CGM system has its advantages and disadvantages. I’ve only worn Medtronic and Dexcom devices so far, so I’ll give my opinions based on them so that I can determine whether CGM will help you manage your diabetes.
Benefits of CGM
data
If you do a blood sugar check on your fingersticks and know your body well, you’ll think there’s a pretty good idea of what sugar is doing in between measurements. But the possibility that you might be wrong is good.
I was a huge surprise when I began to see how much my blood sugar levels actually changed, not to mention the nights I normally don’t check.
CGM is an important tool for providing this type of ongoing information over a 24-hour period, as opposed to snapshots of specific time during the day provided by traditional monitoring.
Suddenly, I was able to see how certain foods and activities affected glucose levels over the next few hours. That information is golden!
Furthermore, being able to find low sugar before a hit (thanks to alerts you set when sugar levels start to drop or when you reach a certain point) actually reduced the frequency of hypoglycemic episodes.
They also catch the less interventions needed to return blood sugar to the target range, so there are fewer glucose tablets and fewer juices to deal with that low level.
management
So, what should we do with all this new information? In my case, it helped me limit the episodes of hypoglycemia (hypoglycemia), but it also reduced my A1C levels (a measure of glucose control over the past 2-3 months) to about 6.0%.
My blood sugar level is always fairly well regulated, but it has never been as stable as ever.
Additionally, some current CGM devices can be integrated with insulin pumps, allowing for simultaneous monitoring of both glucose and insulin levels.
Additionally, certain devices combine CGM and insulin pump technology with an algorithm that automatically adjusts insulin administration, which helps maintain glucose within target range (optimal levels determined by a human healthcare provider), in an innovation known as hybrid closed loop (HCL) technology.
The current HCL devices on the market are:
Of course, just hitting CGM will not control diabetes. However, careful interpretation and use of the data is extremely helpful.
For example, if you sleep at 8am before taking morning insulin, you’ve learned to fight high-morning blood sugar levels until noon.
I also learned what activities will quickly drop my sugar (in my case it’s walking), and that I need my true level of insulin sensitivity throughout the day and at least half of the active insulin (IOB) at all times before training.
This knowledge took time and involved some missteps, but it was life, and it was learning. This information allows for optimizing training and makes it easier to stay within the desired range of 90-144 mg/dL (5.0-8.0 mmol/L) during exercise.
Confidence and security
My CGM has helped me to better understand diabetes. It has given me more confidence in the way I manage my condition and helped me achieve concrete results.
It’s also nice to know how my sugar levels tend to be. I sometimes adventure without bringing all my diabetic gear. Also, I stopped monitoring 10-12 times a day because I don’t need it anymore. Information is always on the screen in front of you.
Using this device allowed me to go for walks and hardcore gym sessions without fear of the lowest possible price, and I was able to efficiently reach both my fitness and diabetic health goals.
Cons of CGM
Accuracy
Anyone who has worn CGM knows they are unhappy with doing traditional finger staining checks and making sure the sensor reading is off.
The reason behind this is that the technology is not yet perfect (although it is constantly improving), so sensors measure glucose levels in interstitial fluids, not blood. (There is usually a few minutes delay between interstitial glucose levels and blood glucose levels)
Aside from obvious issues, it is completely dangerous if you rely solely on sensor measurements and completely ignore what your body is telling you. For example, if you are telling a CGM alarm to be 250 mg/dl (13.9 mmol/l), it is difficult to not respond immediately.
I also had to stop training because the sensor incorrectly said my blood sugar was either low or about to go low.
While some CGM devices are currently highly accurate and are approved by the US Food and Drug Administration (FDA) to make treatment decisions, it is always wise to check for unexpected readings and readings that do not match what your body is feeling with a traditional finger stick before taking action.
(And some devices on the market, including the Medtronic Guardian and Ascensia Eversense E3, require approximately two finger staining checks per day for calibration.)
That said, it is worth noting that the technology has been significantly improved over the years. A 2023 survey showed that CGM was 96.5% accurate in real-world hospital settings.
Overdependence
This is actually the main reason I originally stopped wearing CGM and why I take breaks from time to time.
This may not apply to everyone, but I tend to rely on measurements and recommendations a little heavily. For example, if reading says my glucose is dropping quickly, I completely trust it in how I actually feel. When it comes to diabetes management, I think that’s a big no-no. In this scenario, it is wise to check CGM information with fingerstick checks.
I’ve made management partners a much better partner, not necessarily as a complete truth, but rather a much better partner.
inconvenience
Having the CGM sensor attached to my body all the time can be extremely annoying. It’s not that big and can leave a tan mark that people really don’t notice, but rather unattractive. I also tend to get hurt easily.
When worn on the stomach, it tends to get in the way when exercising, so it usually wears on your upper arm. I get a pretty good read with that arrangement. (One problem though is that it’s a bit difficult to turn off a sweaty sports bra without ripping the sensor.)
Wearing it on my upper arm has created some pretty cool interactions and conversations with curiosity and thriving people. I don’t care – I think it’s an opportunity to educate and advocate for it.
But if that bothers you, there are plenty of other areas where you place the sensor where it is invisible. Typical manufacturer recommendations for sensor placement include upper arms, stomach, hips, thighs and but depending on the particular device you are using.
There are adhesives that help to enhance CGM’s body compliance. See the instructions that come with your CGM and talk to your diabetes care provider about the approach that can work for you.
On related topics, many people wonder if CGM hurts. In my experience, when I insert the sensor, I only get a slight boring feeling. This instantaneous discomfort is worth the data your device offers.
Additionally, for devices currently on the market, the sensors must be changed every 7-10 days (except for the embedded Eversense E3, which usually requires that the healthcare provider change every 90 days).
Related: Below is an overview of my best CGM tips that will explain in detail how to put on the sensor (in video) and how to keep it.
price
Depending on your health insurance, CGM devices and their associated supply can be expensive. Check with your insurance provider to see what costs associated with your CGM.
Final Thoughts
Do you recommend CGM to people with diabetes using insulin? The answer is yes, at least until you understand your body and your diabetes better.
CGM provides you with unprecedented knowledge about diabetes. If you feel that you don’t need it anymore after a while, talk to your diabetes care provider about other options.
The key when using my CGM is to improve listening to both my CGM and my body. It’s a great device, but it’s not a substitute for my own thoughts and experiences.
It’s the perfect tool to be found in my diabetes toolbox, but it cannot stand it on its own.
