How to get the most out of your Expert CGM Insight Experience

Here's an in-depth guide to getting the most out of your Expert CGM Insight Experience

Written by

Dr Claire Merrifield MBBS MRCGP PhD

GP, PhD and our medical director


If you've never used a continuous glucose monitor (CGM) before you're in for a really interesting experience! Being able to get instant feedback on your metabolism is a real eye opener. At first you'll probably only really consider the impact of food but there's so much more to your blood sugar than that. As we'll go into in this deep-dive, context is everything!

To really get the most out of your time with the CGM, I'd strongly encourage you to join our Selph Optimisers Facebook group. You'll get great insights on how a CGM can help you understand your metabolism and my colleagues and I will be on hand to answer any questions, share data and facilitate discussion. Look forward to seeing you there!

What can I expect from my 2 weeks with a CGM?

During the next 2 weeks, you’ll have a fascinating insight into how your body works in real-time. The sensor you’ll wear on your arm will continually check your blood glucose so you’ll be able to see on your phone what your blood glucose is at any point. Our bodies are generally very good at keeping blood glucose fairly constant and how much your sugar goes up and down after food gives us a good idea of how healthy your metabolism is. In general, the more constant your blood glucose is, and the fewer dramatic changes in levels, the healthier you are.

Many people and companies use a CGM as a way to try and decide what they should eat. Although it is really interesting to see what your blood sugar does and how high it goes in response to different foods, please be aware that if you eat the exact same thing on a different day you are unlikely to have the exact same response. That’s because there’s much more to your blood glucose levels than what you eat. We’ll go into this in more depth later on in the experience. For now, try to be curious about what you’re eating, without attaching any worries if you notice your levels going up. It’s perfectly normal for blood glucose to rise after a meal, in particular a sugary meal like a cake. We’re really interested in how much it goes up and how quickly it goes back to normal. Both of these readings tell us how healthy your glucose metabolism is.

In the first week of wearing your sensor, we’ll ask you to take a glucose challenge. In this test, you'll drink 75g glucose (included in your pack) and check your glucose levels at specified intervals afterwards. This "stress-test" gives us a really good idea as to how your body handles glucose.

By the end of the experience you should start to understand how your body responds to different types of food. You might also start to understand how exercise can impact your metabolism and you may have noticed an effect of things like poor sleep and stress. Two weeks is too short a time to change your metabolism, but by understanding how what you do day-to-day can influence your glucose levels, you can start to make meaningful improvements in your life. Our medical team will discuss all of this with you at the end of the experience. It’s empowering how much control you have over how your body works. By identifying any major barriers to health in this experience, we can help you prioritise what’s going to move the needle the most for you over the coming 6 months. You’d be amazed how much simple changes like adding in certain types of exercise to your movement practice can improve your metabolic health.

What should I do with my CGM?

These 2 weeks are not about you abandoning your normal dietary habits because someone’s watching! We’d encourage you to eat the food you normally eat, in the way you normally would. At least for the first few days. Just observe what’s happening at this point and try to avoid worrying about what your sugar levels will do in response to what you eat (there’s good reasons for this which we’ll explain later).

Eat some of your regular meals more than once during the experience. Evidence suggests that even if we eat the same thing, we won’t necessarily have the same glucose response. See if that’s true for you, and if it’s higher on one occasion, see if you can understand what else was going on for you that day.


Try different options for breakfast. You might be surprised how much sugar is in your breakfast cereal. Do you often eat breakfast only to be starving again at around 11am? Try experimenting with a high-protein breakfast that can help you feel fuller for longer. High-protein options that have additional health benefits are eggs, full-fat greek yoghurt and nuts and seeds added into your breakfast cereal.

If you eat toast for breakfast, try eating different breads on different days and seeing what happens. Fresh sourdough bread has a low glycaemic index, meaning it tends to take longer to break down and releases its sugars more slowly than other breads. Take this opportunity to check the ingredients label on your bread. If you buy long-life bread from the supermarket, chances are it’s ultra-processed and there’ll be a ton of ingredients you’ve never heard of before. Real bread should only have 3 ingredients: flour, water, salt (and yeast).

Try different milks. If you tend to drink non-dairy milks in your coffee, try out different milks on different days to see what happens to your glucose levels in response to the different types. Try and keep everything else about your morning the same. You might even want to compare these to cow’s milk.

Remember, just because something causes a lower glucose response, it doesn't necessarily mean it's "healthy". Just another reminder that it is normal for your blood glucose to go up in response to eating. Our main aim is to minimise very high spikes or prolonged rises in glucose. Eating fatty foods tends to decrease our glucose response, so you might find if you were to eat, for example, a plate of fried bacon, sausages and eggs, your blood glucose would be less high than if you ate a bowl of porridge oats with nuts and seeds. But oats, nuts and seeds all have proven benefits for your cardiovascular health, whereas fried bacon and sausages eaten on a regular basis would be detrimental to your metabolic health. There's more to health than just glucose!


Whether you work at home or in the office will play a large role in what you tend to eat for lunch. If you typically get your lunch from a shop, try experimenting with different types of meals that are available and that you like. Again, stop to notice what’s on the ingredients labels of your usual sandwich/bag of crisps/soft drink.

At home, try a few of your usual lunch options. If you eat the same thing quite frequently you may want to see what happens if you make some minor changes to your meal. Changing the type of bread you use in a sandwich or switching to a wrap instead. Trying different variations of salad or soups to see what your blood glucose levels are and also how full it keeps you for the afternoon.


Most of us have highly variable dinners and we would encourage you to try and incorporate as many of your usual meals as you can in this experience. Including the odd takeaway and eating out if that’s part of your usual life.

When you are cooking for yourself, there are small switches you can make to your usual meals to see if they make a difference. For example, if you like pasta dishes, try one pasta dish as normal, then the next time you have that dish, switch your normal pasta for whole grain pasta. If you eat a lot of rice, try swapping jasmine rice for basmati, or wholegrain rice and see if you notice a difference.

If you make switches like this, try to also bring attention to whether you eat the same amount or less and how long you feel full after eating.


Be snack savvy. Test out your favourite snacks and observe your body's response. Try and eat snacks at a similar time each day but vary what you eat. Finding a healthy snack which doesn’t cause a huge rise in your blood sugar can be a great way to help balance your energy. Try our suggestions below:

  • Handful mixed nuts
  • Fruit - try different types of fruit
  • Houmous and carrots, ideally make your own at the weekend and snack on it during the week.
  • Few spoonfuls of greek yoghourt with some berries
  • Protein shake

Make sure to eat any of your usual ‘unhealthy’ snacks while you’re wearing the sensor. There’s no judgement here, but if you notice that having several biscuits or a packet of crisps leaves you unsatisfied and spikes your sugar level, it might make you choose differently in the future.

Make a note of what your blood glucose does in response to your snack choice, and also observe your energy levels an hour or two after the snack - can you find a good option to keep you powered up for the afternoon?


Exercise is one of the most important ways we can manage our blood glucose levels and our overall metabolic health. Make a note of every type of exercise you do in your logbook. You may find that if you do really vigorous exercise, your blood sugar will go up afterwards. Don’t worry and don’t stop exercising if this happens! This is just the body's way of making fuel available. Overall, exercise helps you to store and use blood glucose far better than if you’re not exercising.

If you can, try doing different types of exercise in your week such as moderate intensity exercise like cycling or swimming and then high intensity exercise like HIIT or running. Experiment with exercising at different times of the day. How does it make you feel and does it impact your overall glucose levels?

​​Even if you don’t have a regular movement practice, something as simple as going for a short walk after your meal can improve how quickly glucose is cleared from your system. Give it a try.


One of the easiest ways to reduce unnecessary excess sugar consumption is to stop adding sugar to our drinks. If you have sugar in your tea or coffee, could you bear to have a day without? Just to see what happens? If you frequently drink sugar-sweetened beverages like squash, soda or fruit juices - try drinking them on their own, not at the same time as eating, so you can observe your glucose levels for an hour or so afterwards.

Let’s talk about diet soft drinks and artificial sweeteners. Diet sodas usually contain artificial sweeteners rather than glucose or fructose. They probably won’t do anything to your blood glucose levels if you drink them. This doesn't mean they're "healthy"! There is evidence to suggest if your body expects sugar (by tasting an artificial sweetener for example) then it changes your metabolism. If you really want to improve your health, stick to water, milk, or if you want something more interesting try sparkling water with some pieces of fruit to add some flavour. If you like sugar or sweetener in your tea or coffee, the healthiest thing you can do is cut this out. It takes a few weeks to get used to the taste but it’s worth it!

Sleep and stress

There is good evidence that poor sleep makes us eat more and affects how well our body handles sugar. How stressed you’re feeling also plays a role in how your body handles sugar. We’d encourage you to keep a daily note in your logbook of how good your sleep was the night before and, at the end of the day, note how stressed you were that day.

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