Version 9, May 2025. First published April 2018. NDSSFS010 Print Share on Facebook Share on X Key facts CGM devices are small wearable monitors that automatically measure your glucose level every few minutes, without finger pricks. Each reading shows you your current glucose level, whether it’s rising, falling, or steady, and how different things affect your glucose levels. CGM can help you and your health professional see patterns in your glucose levels to help guide your diabetes management. CGM devices can sound alarms if your glucose levels are outside your target range. You can use CGM on its own or link it with a compatible insulin pump that can automatically adjust insulin based on your glucose levels. People with type 1 diabetes can access subsidised CGM via the NDSS. Your doctor or diabetes health professional can help you apply. Related pages Type 1 diabetes and me Devices and technology Hypoglycaemia NDSS subsidised products Find a health service Find a health professional or pharmacy in your area. On this page What is continuous glucose monitoring (CGM) Understanding CGM readings Accuracy of CGM Benefits of CGM Downsides to CGM How to access CGM Further information What is continuous glucose monitoring (CGM) CGM devices are small, wearable monitors that automatically measure your glucose levels every few minutes. You can quickly see what your glucose level is at any time, without the need for a finger prick. CGM systems have three parts: Sensor The sensor is usually worn on your tummy or the back of your arm. It has a fine, flexible filament that sits under the skin and measures the glucose level in the interstitial fluid (the fluid that surrounds your cells). The sensor is changed every 7–14 days. Transmitter The transmitter is attached to the sensor and sends glucose data to a receiver which displays the readings. Some CGM sensors have built-in transmitters, others have separate transmitters that need replacing every 3–12 months. Receiver The receiver displays your glucose data. It can be a compatible phone or smart device (via an app), a standalone CGM receiver device, or an insulin pump. The receiver also stores glucose data which you can share with your health professional. Understanding CGM readings A CGM reading gives you more information than a finger prick check. You will be able to see your current glucose level, as well as arrows that show if your glucose level is steady, rising, or falling, and how quickly it is changing. You will also be able to see a graph of your glucose levels for the past few hours. Day-to-day, this information can help you decide what action you need to take to keep your glucose level in your target range. You will also see how different things like food, physical activity and stress affect your glucose levels. Over time, CGM data can help you and your health professionals identify glucose patterns and trends, and see where your diabetes management may need adjusting. Accuracy of CGM CGM readings lag behind finger prick blood glucose readings, and so these two readings may not always be the same. This is because CGM measures glucose levels in the interstitial fluid instead of your blood. Glucose travels first to your blood and can take around 6 to 12 minutes to move into your interstitial fluid. This means CGM will be measuring what your blood glucose level was up to 12 minutes before. If your glucose levels are steady, your CGM and finger prick blood glucose readings may be similar. You will see the biggest difference between these readings when your glucose levels are changing rapidly. Times you should confirm CGM readings with a finger prick check include: when your symptoms do not match your CGM reading when your glucose levels may be changing rapidly, for example with physical activity before giving insulin to correct a high glucose level before treating a hypo (hypoglycaemia or low glucose level). Benefits of CGM Benefits of CGM include: Easy glucose checks You can easily check your glucose levels anywhere, anytime just by looking at your receiver device. 24/7 glucose monitoring CGM shows how your glucose levels change over time and how different things affect them. You may also see glucose highs and lows you may not have otherwise been aware of, for example overnight. Trend arrows These show if your glucose levels are steady, rising, or falling and how quickly they are changing, so you make better decisions about how to respond. Alarms and alerts CGM can alert you about glucose highs, lows or predicted hypos – especially useful overnight or if you have hypo unawareness. Fewer finger pricks CGM does not completely replace finger prick checks, but it does reduce how many you need to do. Improved glucose management Consistently using CGM may improve HbA1c and increase time in range (% of time spent with glucose levels in target range). Linking with an insulin pump Some CGMs can be linked to a compatible insulin pump. This allows the pump to automatically adjust insulin delivery based on glucose readings from the CGM. Talk to your diabetes health professional if you would like to learn more. Data sharing CGMs allow you to share your glucose readings with your family, friends, or carers for added peace of mind. You can also share them with your health professional to help guide your diabetes management. Peace of mind Being able to see your glucose level at any time, and knowing you will be alerted if they go out of range, can help you feel less anxious about your glucose levels. Top tips Discuss all the pros and cons of CGM with your diabetes health professional to help you decide if it is right for you. Your choice of CGM device depends on many factors, and your diabetes health professional can help you decide which device may suit you best. To get the most out of CGM, work with your diabetes health professional to learn how to interpret all the glucose data to make better decisions about your diabetes. Downsides to CGM While CGM has many benefits, it is not for everyone and there are some downsides to consider. Being constantly attached Some people do not like having devices constantly attached to their body. Young children, lean adults and older people may struggle to find a site with enough body fat to insert the sensor. Your diabetes health professional can help you find the best sites to wear your sensor. Sensor falling off The sensor may fall off early, especially with sweating or water activities. It can also be knocked off with impact. Tape, adhesive patches and barrier films can help keep the sensor attached. Your diabetes health professional can give you more tips. Skin reactions Some people may have allergic reactions, skin rashes, itching, bleeding, or bruising in the area that the sensor is worn. Trying a different CGM brand may help. Talk to your diabetes health professional for advice. Discomfort You may have some mild pain or discomfort when inserting your sensor, but this is usually temporary. Your diabetes health professional can advise you on reducing discomfort and suitable insertion sites. Information overload It can be overwhelming to see what your glucose levels are doing all the time, including for anyone you have chosen to share your glucose data with. Alarm fatigue CGM alarms that happen often can be annoying and disruptive. Your diabetes health professional can help you set up the alarms to best suit your needs. Data sharing It is important to first consider your privacy and security before sharing your glucose data. Sharing your glucose data is a personal choice and should not put you off using CGM. How to access CGM The Australian Government provides access for eligible people to subsidised CGM products through the NDSS. All people with type 1 diabetes are eligible to apply for subsidised CGM products, as well as some people with other rare conditions that are similar to type 1 diabetes. At present, people with type 2 diabetes are not eligible for subsidised CGM, and it can be quite expensive. Some CGM manufacturers provide a trial CGM pack at a lower cost so you can try it out before deciding if you want to purchase at full price. You can also use CGM occasionally, for example at times when you may need more information about your glucose levels. Talk to your diabetes health professional for advice on accessing CGM. Further information and support Call the NDSS Helpline on 1800 637 700 to ask to speak to a diabetes educator Go to the Australian Diabetes Educators Association website at https://www.adea.com.au/ to find a diabetes educator Learn more about Dexcom CGM devices at https://www.dexcom.com/en-AU Learn more about Medtronic CGM devices at https://www.medtronic-diabetes.com.au/products/continuous-glucose-monitoring Learn more about FreeStyle Libre CGM devices at https://www.freestylelibre.com.au/ This information is intended as a guide only. It should not replace individual medical advice and if you have any concerns about your health or further questions, you should contact your health professional. Sources Healthdirect (2024). Devices to self-monitor your blood sugar. Living Evidence for Diabetes Consortium (2020). Australian evidence-based clinical guidelines for diabetes. Royal Australian College of General Practitioners (2024). Management of type 2 diabetes: A handbook for general practice
