Continuous Glucose Monitors: Your Secret Weapon for Blood Sugar Control

Peter Abraham
6 min readNov 9, 2023


My Abbott Libre Freestyle Libre glucose sensor

In the spring I had my annual physical exam, which included blood tests. My health overall is very good, but a couple things stood out: my cholesterol and A1c glucose tests had been creeping up over the last two years. These markers weren’t dangerously high, but slightly more elevated than you’d expect for someone who exercises 10 hours per week and eats a mostly plant-based diet.

After getting these results, I asked my doctor about trying out a continuous glucose monitor (CGM) for a month or so. She liked the idea and wrote me a prescription. But she qualified this with a warning that “your insurance company probably will not cover the CGM because you don’t have diabetes.” Her prescription was for the Abbott Laboratories sensor, so I downloaded the Abbott Labs Freestyle Libre 2 app from the healthcare giant then stopped in at my local pharmacy. I was picking up two sensors (the round thing you stick in your arm) that each last for two weeks. Abbott Laboratories has a patent on this technology. The cost for the sensor was $185, and I asked if the pharmacist could just call my insurance company and ask about covering the cost. Five minutes later they came back and said my insurance had paid for $110 of the cost, so now I was only out $75. Worth it.

I tried the Abbott Freestyle Libre CGM for a month, then a few weeks later tried the Supersapiens CGM. In total I spent six weeks with these apps. When I say “CGM” what I mean is an app connected to the Abbott sensor that goes into your arm. Both the apps I tried use the same sensor. So the difference in the products comes down to the app experience. The Freestyle Libre is designed for diabetics. So it has built in “low glucose” alarms that must be turned on to use the app. That was annoying because I’m not a diabetic, and overall the UI on the app was poor. The Supersapiens app featured a much slicker UI, and a more intuitive layout.

This is the Abbott sensor that actually goes into your arm

With both apps (Freestyle and Supersapiens) you first attach the Abbott sensor to your arm. That’s the round thing on my arm in the photo above, and it’s got a tiny, painless needle that goes into your skin. The device goes on with a plunger thing that is supplied. It takes an hour of warmup, and then it starts transmitting to your app. The device lasts for two weeks, and then you need to switch to a new one.

What you get is a real time reading of your blood glucose, or blood sugar level, measured in mg/dL (milligrams per deciliter). It’s simplified down to a single number, ranging (for me) between roughly between 50 and 200. At any moment, you can open the app and see the number. Unsurprisingly, the number flattens out while you’re sleeping, then goes up and down depending on what you’re eating and if you’re exercising. There are I’m sure many other factors, but these were the obvious triggers that I was aware of.

I only used these apps for six weeks, so there is I’m sure lots of nuance and data that I did not have time to get into. There are many subtleties within the interactions between diet, exercise and other lifestyle factors. My analysis is not in any way comprehensive. I’m just a middle-aged guy trying to improve his health and sharing what I learned. But given that, I feel like I did take away a lot of valuable information from my own experiment.

The first thing I did once I downloaded the app and get the sensor in my arm was to start eating different things and look at the results. This was the single most important revelation for me: what made my blood glucose spike? My hypothesis going into this experiment was that if I could moderate glucose spikes (both up and down) then I hoped to see some benefit in my cholesterol, A1c, and maybe my weight. My doctor agreed that this was a valid hypothesis to test out with a CGM.

So, first day: big bowl of pasta with very little protein. Immediately the graph on the app showed me a massive upward spike from about 100 to over 200. The next day I tried a slightly smaller bowl of pasta with protein (tofu) and broccoli. The result: a much lower increase in glucose, up to about 150. Interesting! And the experiments go on, day after day. Oatmeal resulted in a suprisingly large spike. Some Chinese or Indian food over a cup of white rice? Yep, that was a spike as well. I tried eating just before and just after a bike ride. As it turns out, exercise moderates the glucose spike.

Here are a couple screenshots 24 hours apart from my Supersapiens app:

Left: almond yogurt with some almonds and blueberries. Right: same thing but with protein powder and chia seeds mixed in, which results in a much smaller spike

I learned through these experiments how to moderate my blood sugar spikes. For me, what was important was getting another set of blood tests after my time with CGM apps. So I was able to compare the same numbers (LDL, HDL, total cholesterol, A1c) before and after using the tool. What I learned is that my numbers all came down 5–10% after using the CGM. I can say with some confidence that my eating habits changed, and this resulted in better blood values than I’d had before I started. I also lost about 5 lbs of weight.

Three blood tests over two years. My total cholesterol, having gone up gradually for 2 years, went from 190 down to 174 during my time with the CGM (between the two tests on the right)

The Supersapiens app can also work with a Garmin or Wahoo bike computer to remind you when to fuel during a ride. In 45 minutes of trying I was unable to pair the app with my Garmin 530 computer. Given Garmin’s terrible UI and UX, this is probably a problem on their side. But I did not get to try Supersapiens for athletic gains.

While I do consider my experiment overall a success, there are a few ways the CGM experience could be improved:

  1. Could either app I used add some motivation to do things that are beneficial? I’m thinking about urging me to do things that do not spike my blood sugar. Is there some kind of nutrition streak I could be aware of? Or gamification (I hate that word) that would keep my spikes on the low side? Are there reminders that could come in as notifications saying “that was a great three days, keep it going.”
  2. Can the CGM data be integrated with other apps (Oura Ring, Whoop, Strava, MyFitnessPal, Training Peaks, etc.) to give a wholistic picture of one’s health? We have access to so many different kinds of health data now, but we don’t get a wholistic picture of how the different things stack up together. Supersapiens is working on a number of these integrations, but I have not used them to see how useful they are.
  3. Can there be more learnings and content sent to me either within the app or via owned channels, like Instagram? The communication from Supersapiens (their Instagram here) is optimized for athletic performance. While I am a cyclist, the biggest upside from the app for me had nothing to do with my riding. It was all about getting my nutrition optimized on a day to day basis. The Freestyle Libre app is targeted at diabetics, so none of their messaging felt relevant for me. The Levels app (which I did not use) is aimed at a more general audience, and their communication feels more in the category of general health.
  4. I feel strongly that a CGM is one of the most powerful tools I’ve used to improve my health. Should there be more messaging about the benefit of this technology? Generally, are CGMs still a secret that the public doesn’t know about? Why is that? And, can we do a better job getting the story out there? Also, why is it so much work to get insurance to cover these? If it provides as much guidance to others than I got, why can’t everyone have a chance to try a CGM?

Based on my own experience, I highly recommend trying a CGM.