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Continuous Glucose Monitoring (CGM) – What Is It?

A continuous glucose monitor (CGM) is a device you wear on your skin that measures blood sugar levels. It works using a tiny sensor (microneedle) that sits just beneath the skin and takes readings from interstitial fluid. This is the substance that surrounds cells and tissues, acting as a bridge between blood and cells, and contains various biomarkers that can be used to assess health. Unlike other forms of blood sugar testing a CGM is worn constantly and therefore provides continuous readings of your levels throughout the day and night. You are able to view the readings of the CGM via a device, usually a smartphone. 


  • CGMS are becoming increasingly recognised as a new means for managing health and well-being more accurately.
  • They are becoming more affordable and accessible to the general public.
  • CGMs have the potential to reveal previously unknown health insights about ourselves.

What are CGMs used for? 

Blood sugar levels, also known as blood glucose levels, rise and fall throughout the day. For people living with diabetes, the changes in blood sugar are larger and happen more frequently than in people who don’t have diabetes. Successful treatment of diabetes, therefore, relies on managing blood sugar levels, preventing it from going too high or too low as much as possible. 

CGMs were originally developed to enable people with type 1 diabetes to monitor patterns in blood sugar levels and manage their condition more effectively. But with the prevalence of type 2 diabetes and a growing awareness of how important blood sugar control is for general health, CGMs are now being used more widely. 

I don’t have diabetes. Can I still benefit from CGM? 

For people with any form of diabetes, prediabetes or insulin resistance,  balancing blood sugar levels is vital for a long and healthy life. Chronic high blood sugar is a major cause of inflammation and metabolic syndrome which also includes central obesity, high blood pressure, high cholesterol, and insulin resistance. It puts you at a higher risk of heart disease, fatty liver, Alzheimer’s disease and some forms of cancer.    

However, even in people without diabetes, blood sugar imbalance is extremely common. Spikes and troughs in your blood sugar levels can occur for many possible reasons such as diet, lifestyle, stress, and illness.

Issues caused by blood sugar imbalance include:

  • Cravings 
  • Hunger 
  • Fatigue 
  • Brain fog 
  • Hormonal and fertility issues  
  • Skin conditions 
  • Wrinkles 
  • Poor Sleep  
  • Menopause symptoms 
  • Mental health symptoms 
  • Low immune response 

We discuss everything you need to know about blood sugar in an earlier post.

The benefits of continuous glucose monitoring

Continuous blood glucose monitoring can be helpful to many people as it can provide insights into what causes your blood sugar levels to go up and down, and particularly how it responds to different foods. Some CGMs also have an alarm feature which alerts you if your blood sugar levels are likely to become too low or too high. This can allow you to take action before it actually occurs.   

Interestingly, recent studies have shown that individuals can have surprisingly unique responses to different foods and features of lifestyle. One person might experience a blood sugar spike after eating a banana but not with a piece of whole-grain toast whereas another person might have the complete opposite response.  Similarly, you may find that vigorous exercise has a balancing effect on your blood sugar levels whilst it causes great fluctuations for somebody else. For anyone wanting to maximise their productivity and optimise long-term health, these insights can be incredibly valuable.

How is CGM different from finger prick checks? 

Traditionally, testing your blood sugar levels at home required obtaining small amounts of blood from your finger using a needle. However, a CGM measures sugar in the interstitial fluid that surrounds your cells just under the skin. Interstitial fluid glucose is not an exact predictor of blood sugar levels, as results can lag behind by up to 15 minutes. Therefore, it is still important for some people, particularly those with diabetes, to use a CGM in tandem with other forms of glucose monitoring such as finger prick tests. (Always seek advice from your healthcare provider).  

Where can I get a CGM?

Currently, in the UK, people with type 1 diabetes can obtain a CGM through the NHS. Because of the nature of type 1 diabetes, ongoing glucose monitoring is vital for the well-being and quality of life of type 1 sufferers. Some types of CGMs can be paired with an insulin pump as an automatic system of dispensing insulin. Some people with type 2 diabetes may also be able to acquire CGMs through the NHS but this is much less common

If you don’t qualify for a CGM, your main option is to self-fund a device. There are various CGM devices available to buy, often with the option of a free trial lasting 2 weeks. Unfortunately, CGMs are not cheap to deploy long term; most sensors cost between £40 and £70, lasting 10-14 days. The sensor links up to a free app on your phone or, if you don’t have a smartphone you can buy a small device called a reader which is a one-off purchase of around £50. 

Whilst long-term glucose monitoring can both provide insight and an ongoing source of motivation towards a healthy lifestyle change, short-term use of a continuous monitor can also provide tremendous value. With some planning and disciplined journaling, ideally supported by a health practitioner or coach, sporadic use of a CGM can help to guide you towards personalised healthy food choices, patterns of exercise, and effective stress management

Improving your blood sugar balance can have a huge effect on long-term health outcomes and day-to-day life.

The benefits of balancing your blood sugar include:

  • Reducing cravings  
  • Increased satiety 
  • Weight loss 
  • Increased energy 
  • Clearer thinking 
  • Improved hormonal balance and fertility 
  • Better skin 
  • Reduced effects of ageing  
  • Better Sleep  
  • Improved menopause symptoms 
  • Better mental health 
  • Improved immune response

At NUVI, our nutritionists, health coaches, and doctors provide support for members using a CGM. We’ll help you to understand your results and how to make small but powerful changes to your diet and lifestyle.  


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