Sophie Morris took a continuous glucose monitor for a test drive and was surprised by the findings
I knew exactly what I wanted to get out of wearing a continuous glucose monitor before I slapped the biscuitshaped device on to my upper arm and pinned it in place with the black plaster provided. I wanted it to tell me that my blood sugar levels were extremely sensitive to something I’m not bothered about eating regularly. Kumquats, say, or pine nuts, and that I could give these up and forget about so-called glucose “spikes” - a buzzword among the worried well.
Continuous glucose monitors, known as CGMs, measure the levels of sugar in our blood - just like a finger-prick blood test - and have become popular among healthy people thanks to the ZOE app. A CGM sends data to an app in real-time, allowing us to monitor how everything we eat and drink, as well as activity levels and stressful events, affect our blood sugar.
I was offered an early trial of Lingo, a new CGM from healthcare company Abbott, and decided to take it on holiday to the US. While a holiday might not sound like the ideal time to be watching what you eat and drink, I wanted to test what I could throw at my body, and how it would react.
There was a lingering fear in the back of my mind that the sensor might be shocked off its own scale by my wine and chocolate habits. But, I reasoned, at least that might make me rethink my intake. The good news? Wine didn’t spike my glucose levels anything like as high as I expected. The culprits were less exciting - and not foods I’m going to give up in any hurry.
WHY BLOOD SUGAR MATTERS
Blood sugar is a hot topic in health and wellness circles and a very serious matter for diabetics. Even if you’re not diabetic, the levels of sugar in our blood, as well as our bodies’ ability to manage any spikes in these levels, can be used to indicate how well we are, and any likelihood of developing pre diabetes. Frequent or too long (over 90 minutes) spikes impact our metabolic health, and thus our propensity to develop certain chronic diseases. Learning to better manage spikes and dips in blood sugar levels could also help to boost our energy and mood.
I guess CGMs offer a way to get ahead of a hangry spell before you’ve eaten an entire packet of chocolate digestives.
After I put the biosensor into my arm - it accesses my blood count via a needle or filament which you can feel but doesn’t hurt - I paired it with the app on my phone by holding my phone nearby for a moment.
According to the app, a typically healthy blood sugar value is 6.5 mmol/L - millimoles per litre measure the concentration of a substance in a certain amount of fluid. I was given a Lingo target count of 60 in the app, based on my age and sex. As you go through the day, your count will creep up, based on your glucose levels.
A value is given to each spike, which adds up through the day - your job is to try to keep within your target over 24 hours. The Lingo algorithm has been developed in this way - to “score” how your blood sugar behaves - to spare you trying to work out if a particular spike or dip is “good” or “bad”.
THE PISTACHIO PASTRY THAT SENT MY COUNT SOARING
I decided on a bold start, and took my CGM out for a six-course meal with paired beer. My blood sugar levels climbed steadily from a low of 4 mmol/L to a high of 8.2. However the “spike” only really got going when I had to run for a train.
Within 40 minutes, it was back down to 4.2. “It’s normal for our glucose to be spiking,” explains Sophie Bertrand, Lingo’s in-house nutritionist. “We don’t want people to be anxious or upset when they see a spike.”
The app assigns some of your Lingo “count” for each of these events; I was given 13 for the big meal, but none for the spike from running. My weekly averages for my trial are 16, 19, 26 and 29, and I only go above 40 three times.
The first is when I kick off my holiday with a delicious pistachio croissant (inset) stuffed full of pastry cream. I follow this with a street taco, a salmon and cream cheese bagel, an ice cream soda float, and finally two beers before an early night. Surprisingly, the beer gave me the lowest count - five - out of everything I consume, while the pastry sent my blood sugar to the highest it ever reaches - 8.6 mmol/L.
Whenever I ate carbs without protein or fat, the spikes were much steeper. Bertrand explains that having, for example, a smoothie with a protein source in it will slow down the release of sugars, and not spike our glucose as much as a pure fruit smoothie.
I think our bodies know this - mine certainly does - based on how we feel after eating something sugary on its own compared to pairing it with protein, but it’s interesting to see this play out for real on the app.
WHAT STRESS DOES TO YOUR BLOOD SUGAR
For the next five days, my counts are below 10. I think this is because I am doing so much activity, traipsing around a city all day, then off to an all-inclusive hotel where we start the day with pre-breakfast swims and go walking and paddle-boarding.
Bertrand tells me that activity levels should have a positive effect on glucose levels, helping to stabilise them. High-intensity workouts can send levels soaring, as can saunas and cold water swimming, but this is generally a natural and necessary response to exercise or healthy stress, she explains. “Even if you’re seeing a spike [during e.g. a HIIT workout], it’s not indicative of your overall metabolic health.
THE TROUBLE WITH OAT MILK
My body coped well when I drank wine, and even dipped a bit when I had a Bloody Mary with a cheese omelette, which seems good news. But Bertrand reveals a fuller picture. “It’s actually quite common,” she says. “Everything else stops when we consume alcohol. Our body prioritises metabolising the alcohol, so it is temporarily not responding to the glucose in our system, or metabolising the proteins, carbs and fats. It’s just trying to rid your body of the alcohol because it’s been identified as a poison.”
The word poison sounds ominous. Is this an extremely negative thing? “Over time, yes,” Bertrand says. “But a couple of glasses of wine on holiday is not going to impact your metabolic health.”
It was more than a couple, but Bertrand tells me I’m in decent metabolic health. Phew. The real surprises were coffee with milk, especially oat milk. When
Starbucks accidentally made me a (huge) iced coffee with oat milk - serving me a venti after I ordered a grande - my levels soared.
Bertrand tells me that some people spike on caffeine itself, though for me it seems to have been the milk, in particular the oat milk. But she tells me not to worry about my coffee consumption, for two reasons. First of all, coffee is associated with managing blood glucose in the long run. Secondly, given it’s a drink I enjoy and my metabolic health seems to be doing fine, there’s no reason to give it up.
WHY BOTHER?
I haven’t tried any other CGMs, and while Lingo wishes to differentiate their own product from market leaders such as ZOE, it sounds like they are very similar. Lingo claims that the ability of its device to stay in contact with the app - rather than you having to frequently lift your phone to the app to connect the two - is an advantage.
It’s not cheap, either. So if it’s your stress levels you’re worried about, you might be better spending the money on taking a holiday or a therapist instead.