How continuous glucose monitors work and much more

Continuous glucose monitors (CGMs), like Dexcom G6, update our blood glucose levels, usually every few minutes.

CGMs like the Dexcom G6 measures glucose levels just underneath our skin and convert this data into a readable graph for the user. For example, the Dexcom G6 will provide an updated reading every 5 minutes to your Dexcom Receiver, phone, or smartwatch.

The dexcom g6 sensor, transmitter, and skin applicator device for type one diabetes glucose monitoring.

In short, CGM systems like Dexcom G6 have three main components. First, there's a sensor that goes directly into the skin to interact with glucose on a molecular level. The sensor then feeds data back to the G6 transmitter adhered to your skin, which beams that information to your device. Some CGMs can even beam data to your insulin pump and help you to create an almost automatic closed-loop system! 

Different CGMs generally have different wear times, with the leading Dexcom G6 at ten days and then the Glucomen Day at 14 days.


What are the benefits of continuous glucose monitoring?

CGMs can make life easier. On average, wearing a CGM saves over 30 finger-prick tests per day. They allow for easier monitoring and checking of your levels. For parents, you can even have your child's Dexcom G6 beam data to your smartwatch or phone - this means you can monitor their blood glucose levels while playing (not too far away!).

CGMs gather lots of data, but fundamentally they can show you the changes in your blood glucose. You can use this data to understand the impact of your lifestyle on your sugars. You'll be able to see how they change as you sleep, after certain activities like exercising, and in regards to almost any other aspect of life.

A continuous glucose monitor graph showing blood sugar highs and lows.

Suppose you're somebody who frequently "rides the rollercoaster" of highs and lows; the CGM data can help you better understand your glucose levels which means that you can test changes in your care to stop these huge spikes and rapid drops. For example, we've found that when we are unwell, our sugars are high for a long time but will crash; therefore, we adjust our care accordingly. 

In a more complex vein, CGMs may also assist with improving your A1C values without increasing the risk of low blood glucose. Currently, there are high-quality data sets that indicate CGMs can help people with type one diabetes keep their blood glucose levels within their target range.

The most significant and most immediate benefit from using a continuous glucose monitor, like the Dexcom G6 or Glucomen Day, is that you can make data-driven decisions on your care. You can see trends and understand how your diabetes reacts to life. Everybody's diabetes is different, and some people's levels change much more than others to the same stimuli. Hence, we must know about our diabetes on a personal level, and CGMs enable this.


But is a continuous glucose monitor right for me?

Only your healthcare provider can answer this question, and you should not take advice that is not from your healthcare provider. Generally, CGMs are helpful to anybody with diabetes because they make glucose monitoring much easier and more convenient. They will benefit the percentage of time our blood glucose levels stay in range and our mental health as well because we can understand our diabetes better and are not having to administer constant finger-prick tests. 

But CGMs are not perfect, and they're not a final solution. Like all technology, sometimes they go wrong, and you will have to do finger-prick tests to double-check the accuracy. We often find that when our Dexcom G6 says we are in a critical low, but we don't feel low, a manual finger prick test shows us to be comfortably in range.


How does continuous glucose monitoring work?

The sensor probe on the CGM can detect minute changes in the glucose concentrations in the interstitial fluid on a molecular level. This fluid lies between your cells and tissues and is separate from your blood. This is also why finger prick blood tests are more accurate because physical compression and other factors can alter the glucose readings from the interstitial fluid.

 The freestyle libre 3 continuous glucose monitoring sensor for type one diabetes glucose level management.

I want one; what's the catch?

Well, they can be pretty expensive, and it depends on where you live. In the UK, you can now get a Freestyle Libre (this is not a CGM, but it's extremely similar) on the NHS, owing to new NICE guidelines. However, most diabetics will have to pay privately if they would like a Dexcom G6. If you have specific needs and are lucky enough to live in a postcode where that CCG or trust has direct funding, you can also get an insulin pump and other tech on the NHS.

For example, in Kent, there isn't much funding for insulin pumps. However, there is a dedicated specialist hub for insulin pump therapy in London, so patients often refer themselves there to get the treatment on the NHS.

Suppose you are in a country with private healthcare, like America. In that case, it's more complicated, and you'll have to go through insurance or pay privately. Combinations of care, like an annual setup of a Dexcom G6 + Omnipod Pump, will set you back over $5,000 personally per annum before we include the price of Insulin and other consumables. Terrifying.

You might also have to buy a reader or receiver if you do not have a compatible phone or smartwatch, which are generally a few hundred £/$.


The freestyle libre 2 and libre reader scanner device to view blood sugars in real time.

There are also associated running costs with CGMs. Some skin types or lifestyles will not work well with CGM adhesives. If you cannot comfortably replace devices, you'll want to protect your skin, device, and wallet with an over patchType One Style adhesive patches are the only medically rated fabric in the world at present, which go around your CGM and protect it from coming off. The protection from the adhesive patch means that you can focus on living your life while passively shielding your CGM. 

Lastly, you'll want clinical backing to get your CGM. When you're going into your endocrinology appointment ready to defend your request for a CGM, or even a pump, you'll need some support. It's beneficial to get approval from your nursing team or another vetted clinical opinion that affirms it is indeed right for you. This clinical opinion is essential because CGMs and pumps are not suitable for all patients.

So who provides CGMs in the UK?

There are quite a few options, but they are for slightly different age groups.

  • Dexcom – You can get the G5 or G6 transmitters as a standalone system or link them to the t:slim x2 insulin pump, which is available for users over the age of two.
  • GlucoMen Day is a single system that lasts 14 days and is available for those over six years old.
  • Medtronic can both be used as a standalone CGM or linked to the Veo or their range of insulin pumps. This range is complicated, and there are more questions about which of their options is most appropriate for people.

There are many important considerations when choosing a CGM. Ultimately, it needs to be a discussion with your doctor or physician. Your technologies impact every part of your diabetes management. You might find that changing one piece of tech can have a knock-on impact on others, so it is not possible to say or decide whether or not a CGM or pump is in your best interests. But that's why we have endocrinologists! 

Protecting your CGM:

As a trusted provider of patches and stickers, we're on hand to advise and support you at every step of your journey. You can explore designs and styles from the menu or by clicking here :)

This information is a guide and might not be explicitly helpful for you. Your friends might be mean or a whole range of things that we, as authors, cannot possibly predict or cater for. This is a guide designed to inform and help those struggling with this topic and no other audience. This guide is also to help non-diabetics understand the perspective of a T1D when this question is asked. The content of this guide is not a reflection, inference, or comparison in any way or form against your circumstances or your understanding of general T1D audiences and groups or your friendship group. If you have taken offense to this guide, please write in detail to We appreciate and explicitly action all constructive feedback.


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