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Notes from midlife

Continuous glucose monitors: should I be wearing one in midlife?

You've seen people wearing continuous glucose monitors and breathing into hand-held devices like Lumen... Here's what all perimenopausal women need to know

Continuous glucose monitors \ blood glucose monitors \ Lumen \ Keyto

midlife woman wearing a continuous glucose monitor CGM

You’ve probably seen people online talking about continuous glucose monitors (CGMs). They are the very latest in a line of wearable devices that promise to revolutionise your health. I'm betting you've also seen the adverts for the Zoe programme. Or else you might well have spotted people wearing a little white disk on their upper arm and wondered, what’s that all about? Then there are those devices you can blow into to measure your metabolic health, and let’s not forget the time-honoured fingerprick blood tests. Want to know how all of this relates to you and, of course, whether you should invest in? This blog is all about continuous glucose monitors, blood glucose monitors and other ways to keep table on your metabolic health so read on...

Why is metabolic health important in midlife & how can continuous glucose monitors (and the like) help?

There is big interest right now in metabolic health and rightly so. Globally we're experiencing an epidemic of diabesity (a term used to combine the dual threat to our health of diabetes and obesity), and this has grim repercussions for all aspects of health for every person who experiences it. If you're reading my blog Notes from Midlife, chances are you're a midlife woman, maybe in perimenopause, menopause, possibly just approaching that age or even post-menopause. Good. Please, please keep reading because this really matters.

As oestrogen declines, many women notice a downhill slide in their health (not all, granted, there are some super healthy/ lucky folk of course) and this can show up as tricky menopausal symptoms like hot flushes and annoying midlife weight gain - the dreaded menobelly, the tyre around the middle that seems impossible to shift. Since oestrogen has a protective effect on your cardio vascular health, shrinking oestrogen levels put post-menopausal women at a significantly higher risk than before of heart attacks and other metabolic problems.

One of the ways you can ensure you are doing the best for your body is by keeping blood sugar levels on an even keel and most women will be completely oblivious to what's going on inside their bodies because, well, if you're not regularly testing and you're not super human, you would have no way of knowing.

Thankfully, in today's tech-driven world, there are all kinds of devices available if you want to look into your metabolic health. As a Registered Nutritional Therapist & Health Coach working with midlife women, balancing blood sugars is a place we always start because the effects of regaining control and keeping on an even keel are profoundly felt across, well, everything: more energy, fewer menopause symptoms generally, weight loss in perimenopause when you might have given up, better sleep, fewer hormonal skin issues and so on.

But now, let's cut to it and talk about those little white discs you keep seeing everywhere...

Continuous glucose monitors (CGMs), Lumen, Keyto... What do these devices do?

Whether you’re talking continuous glucose monitors (CGMs), Lumen or a blood glucose monitor, the reason people are using these devices is that they want to know what their blood sugar levels are as this can be a great insight into your metabolic health.

For some people, of course, measuring blood glucose is a medical necessity. I'm thinking here of people who have been told they have diabetes, for example, and want to get back in control of their glucose levels or, for type 1 diabetes, they need real-time information to work out how much insulin they need to dose. Since very high sugars are dangerous to the body and very low sugar levels (hypos) can be life-threatening, these monitors can mean the difference between life and death.

Over the last couple of years, more and more people who are simply interested in their health are investing in them. You know, the kind of folk some cynics might refer to rather patronisingly as the 'worried well'. These might be people who have been told they have prediabetes and who want to reduce the risk of developing type 2 diabetes (and they have a right to be worried), or those who are looking for answers to why their energy is lacking, or they’re struggling to lose weight, or maybe even those people who love getting data on what their body is doing. Maybe they're not searching for answers but they just love data. Any reason is good enough as far as I'm concerned.

Learning more about how your body works - and not just how the human body works in a textbook - is very addictive.

woman wearing continuous glucose monitor

What's all the fuss about continuous glucose monitors

When you see someone wearing a little disc attached to their upper arm, chances are, it’s a continuous glucose monitor (CGM) or, more specifically, a related device called a flash glucose monitor (FGM). The two terms are used interchangeably although there are some very subtle differences in the way they fetch their readings.

Both devices are 'wearables' designed to monitor blood glucose levels. A CGM continuously tracks glucose levels in real-time and provides continuous updates to the user throughout the day and night. It can also talk to insulin pumps.

In contrast, a flash glucose monitor (like those used with the Zoe programme or the popular brand FreeStyle Libre), takes some automatic readings but it also requires the user to scan a small sensor worn on the skin with a reader or a smartphone app to get the glucose readings. The readings are stored on the sensor and can be reviewed later to get a general idea of glucose trends over time. It can only store eight hours of data, so users typically have to ensure they scan before bed and shortly after they get up just to make sure readings have been taken and there are no gaps in data. If you're looking online for a CGM, chances are it will be one of these...Like I said, they're often used interchangeably so I'm going to continue referring to them as one and the same given the job they do is almost identical.

If you're diabetic, you might be entitled to a device on prescription. If you are simply interested in your metabolic health, you will not. You can take part in the Zoe programme, which also includes a stool test, but there is often a wait of a few months before you can participate and you pay for the entire programme upfront, making it quite pricey.

You can also buy the FreeStyle Libre device from selected pharmacies and also the manufacturer Abbott direct. Monitors last 14 days and cost between £55-75 each.

There are some important things to understand about CGMs and your health:

  1. One way or another, a meaningful experiment with a CGM is going to set you back a few hundred pounds. In reality, just getting one won't give you enough raw data because, even if (in theory at least) you know what you're doing, it can take while to get your head around.

  2. The data from your continuous glucose monitor is super interesting but you've got to know how to read it - otherwise it's a meaningless graph. The free app you'll probably use alongside your device is functional but not insightful. It's just some lines... Whether you're working with a coach like me to turn these numbers into your own 'magic formula' or trying to do this on your own, you will need to invest in another app that helps you see how your food and lifestyle choices affect your glucose levels. It's called Veri. I'm an ambassador because I think it really is a great product that brings meaning to blood glucose monitoring.

  3. For some people, this level of knowledge is not healthy. If you have an unhealthy obsession with the scales, knowing your blood glucose levels is going to be one extra thing to have a bad relationship with and to obsess over.

  4. View your CGM readings as a general trend not the be-all-and-end-all. If you have any kind of health anxiety, a continuous glucose monitor is not going to be your friend. In fact, the opposite. Wearing a CGM in this instance will drive your anxiety and keep you in fight-or-flight stress mode. This in turn will push up your blood glucose levels, which further fans the flames of alarm. If this is you, do not buy a continuous glucose monitor.

  5. It's natural for your blood sugar levels to go up and down for all kinds of reasons. Yes, with the food you eat but also with stress, lack of sleep (which is in and of itself a kind of stress) and exercise (another source of stress on the body but a positive one). Heck, my blood sugar spiked when I got to a particularly sad bit in the Eddie the Eagle Movie (don't judge!) And when I starting getting sick with a cold, my continuous glucose monitor went into overdrive. My levels were through the roof. Had I not been wearing a monitor, I'd have been none the wiser and in this instance, that might have been a good thing. Again, if you're just looking at the free app that comes with a continuous glucose monitor, it will be difficult to see an effective timeline and be all 'oh yeah, that spike was when I ....' You entirely lose the context. And that is why I totally recommend the Veri app if you are tempted to buy a blood glucose monitor.

  6. Wearing a CGM might not give you all the answers you're looking for. If you're wondering 'should I wear a continuous glucose monitor to help me lose weight' or else 'will a CGM help me manage my menopause', the answer might be yes but it equally might be no. Wearing a monitor will give you some information but the human body is complex and it might be that you need a little more unravelling. Other forms of testing - like blood, stool or genetic tests - might be even more illuminating. And this is why you might see other nutrition professionals knocking CGMs. It's not that continuous glucose monitors are a bad idea but they might not be right for you. But that's normal, right?

Ultimately, knowledge is power. And that's why I'm a fan of continuous glucose monitors

Lumen & Keyto devices

lumen device for measuring metabolic health

Both Lumen and Keyto are handheld, portable devices you breathe into and promise to ‘hack your metabolism’. They look a bit like a vape. They come with an app you synch to the device. The device measures elements in your breath to decide whether you are burning fat or sugars as your main source of fuel. They’re designed for people who want to lose weight (by being in fat burning rather than fat storage mode) and anyone else who is fascinated by the workings of their metabolism.

What is Lumen and how can it help me?

Lumen analyses the carbon dioxide (CO2) levels in your breath to work out whether you are mainly using carbohydrates/ glucose for fuel and fat (high CO2 means low fat burn, low CO2, fat burn). It then gives you a ‘Flex Score’, which is their measurement of your metabolic flexibility, which is in itself a term used by main in the health industry to describe how well your body can switch between burning carbohydrates/ glucose for fuel and fat.

The most metabolically flexible among us will be able to effortlessly switch between both fuel sources. If you’ve spent years on a high carb or high sugar diet, you can get stuck in glucose-burning mode and will need to train your body back to flexibility.

The feedback and tips can help you make different food choices, which suggestions for the amount of grams of carbs, fat, etc. you might eat that day. If you wake up with a nice, low Flex Score, this shows your body is burning fat, and this is a good thing. If your early morning reading is on the high side, this shows you’re still burning off the glucose from the night before, and the app will guide you to making lower carb choices for the day to help improve your score.

Lumen costs from £245 for the device and three month’s access to the app.

What Keyto can tell you about your metabolic health

keyto breath test device to measure ketosis

Keyto also uses your breath to work out whether you are using sugars or fat for energy. In this case, it measures levels of acetone in your breath rather than CO2 (like Lumen). It’s aimed at the keto market – people who are on the ketogenic diet (a high fat, moderate protein, low carb diet) for health or weight loss reasons.

Acetone is more readily detected in your breath when you are in ketosis. Typically, on a keto diet, people might use fingerprick blood monitors (very reliable) or urine strips (only reliable when you start the keto diet, becoming less reliable the longer you stay in ketosis). This device makes it possible to stay in ketosis without sticking your finger.

Keyto also comes with its own app, which has food trackers, meal plans, recipes and support. The device ($99) and app ($49/mo) are sold separately.

blood glucose testing kit

What you need to know about blood glucose monitors

These pocket devices have been around for years, and you can buy them from pretty much every pharmacy and online. They usually come in a kit with a lancing device that spikes your finger, releasing a little drop of blood and a pack of testing strips. You insert a glucose testing strip into the machine and drop the blood onto it and, within seconds, you have your reading. They cost less than £15/$20 so they are a great starting point for measuring your blood glucose levels that won't break the bank.

Diabetic patients would test their glucose levels at different points in the day, perhaps first thing in the morning (this a good general indicator of blood sugar management), right before a meal and then 2 hours after a meal (when levels should fall back to the baseline level). If you don’t have diabetes, but you have prediabetes or you just want to know what your body is telling you, it’s most likely you’ll measure first thing in the morning, just after you’ve got out of bed and before having a morning cuppa or anything to eat. This is your fasting glucose reading.

Your doctor may routinely have taken a fasted reading like this if you’ve ever had blood taken. It’s considered a reasonably poor measure of your blood sugar levels but the essential thing to note is that it is just one moment in time – literally the time you pricked your finger – and it might have been different yesterday and it might be different tomorrow. This is why having your own kit can be helpful, and it is also why doctors who are genuinely interested in what your blood sugar levels have been doing over time would test your HbA1c.

HbA1c stands for hemoglobin A1c, which is a blood test used to measure the average blood sugar levels over the past three months. Hemoglobin is a protein found in red blood cells that carries oxygen to different parts of the body, and glucose can attach to it, forming a "glycated" hemoglobin molecule.

The HbA1c test measures the percentage of glycated hemoglobin in the blood, reflecting the average blood sugar levels over few months. This is why it’s more interesting for medical professionals to know what this number looks like for their patients rather than a single measurement taken on the one day they were in the blood test centre. You can get your HbA1c done privately and relatively inexpensively. It’s a test I often recommend to my clients.

testing ketosis with a blood ketone monitor

You can also buy similar monitors to measure your ketone levels if you’re a fan of the ketogenic diet. Some machines can measure both and you would need different strips to measure ketones to the ones you use for glucose. Otherwise, the machine works in the same way. The drop of blood, in this case, indicates whether you are in ketosis or not.


Morning fasting glucose levels should be between 4mmnol/L and 5.4mmol/L (72 to 99 mg/dL) for non-diabetics.

5.5 to 6.9 mmol/l (100 to 125 mg/dl) may be indicative of prediabetes.

7.0 mmol/l or more (126 mg/dl or more) may suggest diabetes.

If you are measuring your fasted sugar levels and get a reading you don’t like, don’t jump to conclusions. If you have a few consecutive readings, make an appointment to see your doctor. There are a few things outside of food and drinks that have an impact on blood glucose readings, not least stress.


If you're following a ketogenic diet, this is what you need to know. Nutritional ketosis begins at 1.0 and an optimal therapeutic zone is between 3.0 and 5.0.

My considered view

I own ALL of the above with the exception of Lumen, which I have read a lot about and would love to try but really cannot justify spending money on since, well, I do have all the others. Continuous glucose monitor? Check? Blood glucose and ketone monitor? Check. Key? Check. I genuinely do use them. Not all the time, of course. I've dabbled in and out of keto in the past and have used both the Keyto device and the blood monitor (the latter just to double check the calibration of the former, but this really isn't necessary - give a girl tools...) I really do like my continuous glucose monitor but it's really pointless unless you also get the Veri app so you can add 'events' like what you ate for lunch, snacks, coffee, booze, pull in your exercise from a health app, and so on. I've been sporting mine for about 6 weeks continuously just to get a feel for every aspect of it since I am also part of the new Veri coaching programme for practitioners, which means that clients who work with me can share their Veri data and we can use that alongside a programme. Super cool, yes? I won't always wear mine but I will dip in and out over the year to keep an eye on my metabolic health. After all, I'm a menopausal woman and metabolic health is essential...

An invitation

If you're a woman in midlife and want to get a better handle on your health, let's talk. I offer all prospective clients a free 30-minute mini consultation to help create a strategy for them to move forward in an area of their health. You can book your place here.

Interested in the Veri app? Click here to get $30 off using my affiliate code.


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