I've been using blood glucose trackers on and off for the last year - and what they've taught me about my body has been game-changing

Seen the arm stickers doing the rounds?

Zoe review: A blood glucose tracker in Ally's arm
(Image credit: Simon Roberts)

When blood glucose monitors first started popping up on my social media feeds at the end of 2022, my interest was immediately piqued. As a Health Editor with eight years of industry experience, it's my job to sift genuinely helpful nutrition tools from pointless fads and then write about my experiences in the hope that you won't make the same mistakes I did.

And trust me, there's been a lot of them - from no carb diets, to 6am fasted HIIT workouts, to questionable supplements that cost the earth, the wellness world is saturated with "must tries" that - well, aren't really must tries for everyone. Next in line? Continuous glucose monitors (CGM) from the likes of Zoe, Lingo, and more promising to help you work out what foods work best for your body and which don't.

Personalised nutrition is really having a moment, and with recent health-tech advancements making it even easier to gain real-time insight into how your body works from home, it's no wonder the whole of the UK seems to have jumped on the bandwagon. Celebrities including Davina McCall, Carrie Johnson and Steven Bartlett all rave about the benefits they've noticed since using CGM's (Bartlett has even invested in one app, Zoe) and it's without doubt one of the topics I get asked about the most among industry colleagues, friends, and even family.

To put into context how popular Zoe has become over the past year, the app currently has over 100,000 subscribers paying up to £600 for the first year. Wondering what continuous glucose monitors like Zoe are, how they work, and whether they could actually benefit you? I've personally tested a blood glucose monitor, and trialled the recommended blood glucose-friendly diet, for the past year and cannot put it any other way: it's changed my life. As a Health Editor who believes that nutrition is a highly personal and nuanced subject, I also love the fact that the new "must try" isn't a one-size-fits-all approach - rather, a deep dive into your body and what genuinely works for you. But that's not to say I think they're for everyone. For my full review, keep scrolling.

I've been trying blood glucose monitors for a year now - and while they've changed my life, I don't think they're for everyone

Let's rewind to last year. The buzz around blood glucose monitors was in its early infancy and, while a few notable figures had endorsed brands like Zoe, the monitors were largely still used by diabetics to monitor their blood sugar spikes.

That is, until health-tech brands started raving about the benefits we could all see from embracing a more blood-sugar-friendly diet. As someone with polycystic ovarian syndrome, I was all ears. You see, I'd been told by medical professionals that women with PCOS can't process glucose in the same way others can and so often see far more drastic blood sugar spikes from certain foods and meals. Frequent blood sugar spikes, in turn, can lead to inflammation in the body, which presents in the form of weight gain, acne, insomnia and brain fog. In a nutshell, I was constantly feeling at a 70% despite leading a seemingly healthy lifestyle.

The problem is, you see, while there's plenty of generalised advice about which foods spike blood sugar levels and what to eat if you have PCOS, I never knew which particular foods didn't work for me and my body. While experts will often advise you to opt for low or no-carb diets, as a Health Editor who followed a low-carb diet for around two years in my early twenties, this just wasn't something I could get onboard with as being "optimal" for my health. Carbs are essential in our diet as they provide our bodies with glucose, which is converted into all-important energy. I'd been there, done that, and it only led to periods of following all-too-restrictive, generalised diet "rules" that left me miserable and low energy. 

Month one

Biting the bullet and deciding to give the personalised nutrition thing a go, I started 2023 by sanitising my left upper arm and pushing the thin spike of a blood glucose monitor into my bicep. My first experience was with a brand called Levels which, for the time being, is still only retailing in the US (their plans for UK expansion were shut down last year, the reason why as of yet undisclosed).

The process, despite being a bit intimidating to begin with (no one likes pushing a needle into their arm) was straightforward, not to mention rewarding as you could track your data instantly via their app. Spoiler alert: I was instantly hooked. Being able to see what was happening inside my body with a simple scan of my arm? I can't stress enough - fascinating.

Day one and I opt for protein-boosted porridge topped with seeds, blueberries and peanut butter for breakfast - a meal I'd consider balanced, with protein, fat and carbs all at play. Just a mere 45 minutes later, though, and my blood glucose starts to spike way off the chart, made no better by the date and chia Bounce ball (again, something I considered a fail-safe healthy snack option) sending it sky-rocketing mid-morning.

Day two, and a lunch of puff pastry vegetable tart, roasted carrots and beetroot does the same. Later that evening, I realise I'm compulsively checking the app every two minutes at a press dinner, despite the meal being basically all protein. Starting to feel disheartened and unable to figure out the patterns of what's making me spike and what isn't, I take a few days off from checking the monitor all the time, stripping things back to basics.

As the weeks go on, I do get to grips with what works for me and my body more - that said, my average blood glucose level still rests at around 6 to 8 mmo/l, a “healthy” target range being between 4 and 7mmol/l.

Another interesting breakthrough comes on week three, where I notice that my blood sugar spikes significantly less if I eat my vegetables first, then my protein, then my fat, then my carbs. I like this approach as it means I don't have to eliminate anything from my diet - rather, just eat my foods in a certain order.

That said, for full transparency, I found the first month of using the Levels blood glucose monitor a little overwhelming. There wasn't enough data to confirm what was making my blood glucose spike, or confirmation of what was a "healthy" normal range, meaning I was left feeling quite anxious viewing my blood sugar spike all the time with no real clue of how to level it out.

Months two to eleven

For the next ten months, I decided to take matters into my own hands, utilising what I'd learnt from Levels but following a blood sugar-friendly diet without a tracker in my arm constantly telling me what to do.

That's because I know that I'm the type of person who finds data a little overwhelming at times - overload is real and can actually negatively impact our mental wellbeing more than benefit it, as this survey from ESHRI highlights.

Discussing this at length with biomechanics coach Anthony Fletcher of OneTrack Club, he reflected on the fine line between useful and informative data and data tracking that errs on obsessive. We both agreed that ultimately, we know our bodies best and, while data tracking can undoubtedly be a useful tool, it's not necessarily something we need all the time for optimal health and wellbeing.

Taking onboard the nutrition advice provided by Levels, I also spend hours researching advice from qualified dieticians and nutritionists and start following French biochemist Jessie Inschuppe, otherwise known as The Glucose Goddess. They all recommend the same Glucose Goddess hacks: opting for no naked carbs (rather, a balance of protein, fat and carb with every meal), swerving coffee on an empty stomach (instead, having it after my breakfast), eating savoury breakfasts, and enjoying sweet treats after meals, too. 

The reason I think this lifestyle overhaul actually stuck is because eating to stabilise blood sugar spikes doesn't mean cutting anything out or emitting foods you love - rather, adding to your diet to make said meal or treat more balanced and digestible for your body. (Think a veggie starter or apple cider vinegar drink before a carb-heavy meal, or sweet treat as a dessert rather than in the middle of the day). As someone who grew up bombarded with the diet culture of the noughties, it was refreshingly normal - eat what you normally eat, but rethink the structure or add some veggies in, too.

Using the blood glucose tracker had been invaluable as it had helped me to identify which "healthy" meals I'd been eating that weren't all that healthy for me and my body. Oats, for example, don't work for me on their own, but porridge with yoghurt and seeds leads to a smaller spike. Interestingly, rice spiked my glucose levels far more than pasta, and while most breads and beer didn't do great things spike-wise, sourdough, rye and (hilariously) champagne were all absolutely fine. (No complaints on the last one). 

While I could chat about this for hours, and as my friends, family and colleagues well know, it'd be the understatement of the year to say this changed my life. Spurred on by the data I'd initially seen on Levels, I knew I had to get my blood sugar spikes in check - but what I couldn't have foreseen was what a significant and noticeable impact it would have on both my physical and mental health. Come the end of 2022, for arguably the first time in my life I had clear skin, my brain fog had all but disappeared, and I'd lost a little weight, too (one friend endearingly called it my "accidental glow up"). The main benefit, though, was my energy, mental clarity, and all-round zest for life - I finally felt like I was fuelling my body in a way that worked for me. Not to mention, my periods - for years irregular and quite frankly a pain - are regular. 


Zoe 🤝 no more gut pains. A snippet from a long interview with the zoe team, about health, habits and goal setting. If this resonates, i’d reccomend watching - Link in bio 💛 (AD - i’m a user and now investor of the brand )

♬ original sound - Steven Bartlett

Month twelve

Come the start of 2023, an email landed in my inbox from Lingo, another blood glucose monitoring app from healthcare company Abbott. I'm really keen to see if my year of eating to stabilise my blood sugar spikes has actually paid off, if a little nervous. So off I go again, sanitising my arm and repeating the all-too-familiar procedure of popping the needle in.

From the get-go, I find the Lingo app far easier to use and user-friendly than other competitors. Giving you a daily "target" to aim for based on your data, what's great is that the app accounts for the normal blood sugar spikes that we all see day in, day out, leading to a far less anxiety-inducing experience.

To my amazement but perhaps not surprisingly, the app tells me that my resting blood glucose level is now sitting at around 5 mmol/l, comfortably within the “healthy” target range and a fair few points lower than a year ago. All of the meals that I've now incorporated as part of my daily lifestyle keep my blood sugar stable throughout the day - eggs, PB and rye, or chia pudding for breakfast, veg and protein-packed sandwiches, salads or stews for lunch, and another veg-protein-fat-carb iteration for dinner. Experiencing a blood glucose tracker the second time around was far less anxiety-inducing as, when I did have a particularly spike-inducing meal (think pizza or pancakes), I knew it was a one-off, not the norm. 

Using the trackers has empowered me more than I will ever be able to iterate - after years of struggling with my PCOS symptoms, I finally feel like I know how best to eat to boost my body and mind. For that reason, I'd encourage anyone who feels their diet might not be working for them to give it a go. One thing I do feel quite passionately about, though, as these trackers continue to soar in popularity, is that it's absolutely essential that you don't take what an app is telling you as absolutely gospel. While nutrition is key to a healthy life, so is enjoying food that brings you joy, meals out with family and friends and holidays where you eat ice cream every day. Sure, these won't be "optimal" for your glucose spikes, but they are essential for your mental health.

Similarly, I do feel CGM's are a useful tool to use over a short time period, not all the time. They should be educational and a way to teach us how best to look after our bodies - I don't think it's necessary to wear one all of the time, especially once you get to grips with what works for you. Worth noting is the price point, too - they're not cheap, but again, if you utilise it as a one-off tool to educate you for life, I think they can be invaluable.

So, what do the experts reckon about blood glucose monitors offering personalised nutrition advice?

According to Pamela Nisevich Bede, global nutritionist for Abbott's Lingo, continuous glucose monitors (CGMs) like Lingo are designed to help people gain a better understanding of their glucose in order to create healthier habits and improve overall wellbeing. "Managing your glucose curve can lead to significant health benefits such as boosting energy, managing hunger, improving mood, increasing focus and getting better sleep," she explains.

So, is there scientific evidence to back up these claims? Short answer - yes. "One study showed that people following a low-glycemic diet reported feeling over 20% less fatigue and 55% better mood than when they ate a high-glycaemic diet," she shares. On the other hand, another study found that those who ate a high-glycaemic diet had a 55% higher report of poor mood. "So often, we attribute these factors to external daily occurrences, but it’s so interesting to note how they can be increased with simple and sustainable behaviour changes."

It doesn't stop there, either - further research has proven that the long-term benefits of glucose management are wide-reaching, ranging from maintaining a healthy weight to improved metabolic health, and even improved skin appearance, she goes on.

She makes the key differentiation between medical CGMs and wellness CGMs here, too - the former designed for people managing a medical condition like diabetes and the latter, for consumers to help them understand their personal metabolic health.

She reckons that, if you’re someone who wants to understand more about how to improve their lifestyle with small, sustainable and manageable healthier habits, it's a no-brainer to give one a go. "The information you see empowers you to make decisions that help you live healthier - everyone is individual and has a different reaction to the food they eat and life’s daily stresses," she shares. "Seeing the information in front of you, in real-time, takes away the guesswork."

And what about independent experts?

So, what do nutritionists who aren't associated with the brand reckon? According to Clarissa Lenherr, blood glucose trackers can be great tools for helping you make informed decisions about what you eat and how you live.

Nutritionist Uta Boellinger agrees, adding that understanding blood glucose levels and blood sugar balance is one of the foundations of health and nutrition and something she teaches to all of her clients. "Frequently spiking blood sugar levels has such wide-reaching effects on our bodies, from weight gain, to low energy, to inflammation, to increased stress and anxiety levels. It can even impact your fertility," she explains.

"However, not everyone needs to worry about their blood glucose levels all the time," Lenherr stresses. "Stable blood glucose is beneficial for individuals, especially with specific health conditions, but the blanket notion that everyone should have constant stable blood sugar levels may actually do more harm than good."

Case in point: she stresses that some people might feel like they have to optimise their diets to keep their blood sugar steady, which could lead to restrictive diets and an unhealthy relationship with food.

Nutritionist Jenna Hope agrees, further reinforcing that CGM's can be helpful for a select number of individuals (namely those with diabetes, PCOS and insulin resistance). "That said, they can sometimes cause anxiety around food, specifically carbohydrates," she points out. She does agree that most of the principles associated with stabilising blood glucose levels are definitely good practices for general wellbeing, though. "For example, combining protein with carbohydrates, walking after a meal and avoiding caffeine on an empty stomach are all great tips," she goes on.

Know this: "It's normal for your blood glucose levels to go up and down throughout the day," Lenherr shares. "Things like when you eat, what you eat, and how active you are can all affect your levels - and this doesn’t make you an unhealthy person. Obsessive monitoring and trying to reach constant stable levels may divert attention from the broader aspects of a balanced and sustainable approach to nutrition."

Another important point to note - for the average individual, there are so many factors which can impact how much a food spikes your blood glucose. "Consuming the same food on a highly stressful day or off the back of a poor sleep could elicit higher glucose spikes than when you’re not stressed or you’ve slept well," nutritionist Jenna Hope adds.

Lenherr and Boellinger both advise exactly what I did - experimenting with using the device for a few weeks to educate you without risking data overload. "This could help you gather information about how their body responds to different factors, allowing you to make positive changes in your habits post-use."

Boellinger concludes by adding that she believes everyone in the UK should be optimising their diets towards more stable blood glucose levels. "Having said that, I don't believe glucose monitors are necessarily always required. Most people can be taught the concept and implement strategies (all of what you mention: eating veg before meals, no coffee on an empty stomach, less sugar and after a meal, putting clothes on carbs, etc) with great results without the need to see their glucose levels on paper," she concludes. 

Ally Head
Senior Health, Sustainability and Relationships Editor

Ally Head is Marie Claire UK's Senior Health, Sustainability, and Relationships Editor, nine-time marathoner, and Boston Qualifying runner. Day-to-day, she works across site strategy, features, and e-commerce, reporting on the latest health updates, writing the must-read health and wellness content, and rounding up the genuinely sustainable and squat-proof gym leggings worth *adding to basket*. She's won a BSME for her sustainability work, regularly hosts panels and presents for events like the Sustainability Awards, and saw nine million total impressions on the January 2023 Wellness Issue she oversaw. Follow Ally on Instagram for more or get in touch.