Review: Supersapiens Constant Glucose Monitor

If you are a diabetic, you might be looking at this article saying, “Those look bloody familiar to me!” And you’d be right. The heart of the system is the Abbot Libre sensor, which is a mildly adapted version of Abbots’ medical sensor for diabetics. So before we go any further in this review let us get the big question out of the way - does the technology work? Yes.

The Supersapiens tech was originally designed as a monitoring device for people whose lives depend on managing their blood sugar. The sports versions are marked “not for medical use” and have the option to connect directly to your phone, so they are a little different and it is fair to assume they are produced to a slightly more relaxed standard, but it is a well-proven, dependable system. So for the rest of this review, we will be focusing on the more interesting question of why you might want it to work.




Getting Started

The heart of the system is the Libre Sense sensor. Essentially it is a tiny needle that sits just beneath the skin for the two weeks the sensors work for.

Popping open the box, the initial setup takes a moment to figure out, but if you follow their instructions it is straight forwards. You need to clean the skin on the back of your arm first as the patch is going to be in one place for a fortnight. You then assemble the applicator and press the sensor on. Depending on the spot the sensation ranged from nothing at all to (unsurprisingly) a minor needle-prick.

If you are at all clumsy then the protective cover is worth using. Scraping a door frame as I walked through I accidentally peeled the first sensor I used off my arm and once they come off they cannot be reapplied - a frustrating way to bin €75.

With the sensor on the back of your arm, you then need to connect it to a device. Supersapiens say that compatible phones need NFC technology (the system contactless payments use) and enough punch to be able to handle the app. Unfortunately, the iPhone SE (2016) I was running did not make the cut. To run the test I had to upgrade to an iPhone 12 Mini and from then on it paired flawlessly. It is also worth noting that my Garmin Fenix 3 was also too old for the system - so if you are considering going down this route you need to make sure that your tech is capable.

Once you are set up and paired to your phone, you need to wait for an hour for the system to warm up. From then on you will have live updates of your blood sugar.

Using Supersapiens

On their website Supersapiens split the three areas they believe their tech is most useful for: prime, perform and recover, so from here we will split this review into those three categories to have a look at what the system might do for you.

Prime

We all know that if we want to do a big ride we need to eat plenty beforehand. We have all learned that we should eat something which provides enough energy for us, but do we stop to think about what foods provide the best levels of energy? Many common foods can actually cause your blood glucose to spike, which means inconsistent energy levels.

That blood sugar spike is the same mechanism diabetes uses to damage the body, primarily through inflammation. While the effects are less dramatic in people who can naturally control their blood sugar, it is something we should try and avoid, both for our long-term health and our sporting performance.

The value of a constant glucose monitor is that we all respond a little differently. While you can find general guidelines as to good things to eat, if you are looking to maximize your performance you can use it to test and verify fuelling strategies. You can run a series of everyday experiments on yourself to have a data-supported picture of which foods work do and don't work for you.

To give a personal example, I eat porridge for breakfast with raisins and cranberries every day. The Supersapiens told me that something in that mix was causing a big blood sugar spike. On the first day, I tried the breakfast without the raisins, the second without the cranberries, and the third with neither. It turned out that it was the cranberries that were causing the spike. Since removing them I have noticed that I don’t tend to run out of energy mid-morning as often.

By following your glucose levels you can start to work into granular details of your diet too. For instance - how long should you give yourself after eating before sport? This is a very individual thing, we all vary in this respect. Ideally, you want quite a high level of blood sugar to get the most out of your body, so how long after feeding is that point?

For endurance athletes, this benefit is pretty straight forwards, but it can also be used for more intense disciplines, like DH. If you are honing in on every little detail to make those three minutes between the tapes as perfect as possible, surely you should make sure that you have the optimal amount of energy available?



Perform

It is worth noting that the UCI has banned this technology in competition. This may seem an odd decision to those who don’t follow road cycling closely, but it is probably a good thing. Take the Road World Championships, usually something like an 8-hour race for the men. Fuelling is a critical part of the skill of racing, especially over a huge day like that. If a rider gets it wrong, the critical moment may come and they have no energy to respond.

To excel at endurance racing you need to learn to manage your body through the day. With a constant glucose monitor, you can be notified of your blood sugar levels beginning to dip before you would be able to feel it, meaning that to be perfectly fuelled you simply need to watch a number, no skill required. This reduces the one factor racing needs to be exciting - unpredictability.

If you have done your homework in the priming phase you can then choose what to fuel yourself with based on how you respond to it. For instance, while the sugar spike from cranberries was a bad thing at breakfast, out on a ride when I may want to raise my blood sugar levels as quickly as possible, that could be a positive thing. One thing the app does help you start to understand is that you need different blood sugar levels for different situations, and correspondingly you can start to match different foods to those situations.

In the saddle, it was very interesting to see how different intensities affected blood sugar levels. In early summer I took on the climb above our village affectionately known as “The Death March” - a long, exposed fireroad where the gradient always seems to be against you. Keeping an eye on both my blood sugar and heart rate, I could see that if I let my heart rate go too high my body would dump sugar into my blood to respond, which would be followed by a big crash in glucose.

A week or so later I tried riding a road climb while strictly controlling my heart rate. That constant heart rate meant I could do the 25km climb with no spikes or crashes. However, what I discovered after was that riding like this (without food) meant that I severely depleted my glycogen stores and it took a few days for them to recover and be able to ride again.

Recover

The Supersapiens app tells you that there is a 30-60 minute “insulin-independent” window after exercise to replenish your glycogen. In other words, they give you permission to stuff your face in the name of optimal recovery, which I definitely approve of.

It was during this phase I had my biggest epiphany with the Supersapiens. For years I have noticed that when I take a rest week, after two to three days I crash heavily for three days or so. It has always been one of those things I knew I had to accept, but it always frustrated me. By monitoring my glucose I learned that this is due to blood sugar - after two days' rest, my blood sugar levels fell off a cliff and took around three days to normalize. It may not offer a practical advantage to me at this stage, but understanding what is happening and why made it far easier to accept.

Limitations

The biggest limitation with the system, for me, is the memory in the sensors. They can hold up to eight hours of data, which is not enough. Most of us know that eight hours is a good amount of sleep, especially if you are training hard, but when you start thinking practically about it, you see that it is not long enough. For eight hours’ sleep, sleep specialists tell us that we should take something like 40 minutes without screens before bed, then you need to factor in the time to fall asleep (20 minutes is considered optimal), then time to wake up in the morning (apparently avoiding screens for an hour first thing is a good thing to do). So for eight hours’ sleep, you should be looking to put your phone down for 10 hours, leaving you with a two-hour gap in the data.

It is hard to avoid the cost question, too. A monthly membership package costs €150 per month, which is a lot of money. They also offer tailored packs for 10, 14, and 18 weeks, which correspond to popular training blocks.

If you are sitting there thinking that sounds expensive, chances are that this is not the product for you. For many, this level of data will change their training forever. When I was stuck into a serious block of cardio I was doing mental arithmetic trying to figure out how I could afford to run the system year-round. Then, over the summer, I checked out from my cardio program for various reasons and lost interest in glucose monitoring. Much of how you feel about Supersapiens will likely be tied to how seriously you train - if you watch a major road race these days, even the support staff are using Supersapiens.

That said, the way Supersapiens helps you learn, maybe you don’t need it 24/7? For instance, a monthly pack is €150, which is around half an annual Whoop subscription, but in that month you could experiment and use that information to inform the rest of your season, or life.

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Pinkbike's Take

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