Continuous Glucose Monitoring (CGM)

How CGMs work

CGMs operate by using small sensors that are placed under the skin. The specific location for insertion varies depending on the device, but it is typically in fatty tissue that can be easily grasped to ensure comfort when worn. Commonly recommended locations are similar to where a person would inject insulin: the back of the arm, the stomach, the outer thigh and the upper buttocks.

The sensors are connected through a needle or a catheter, which transmits glucose levels to a receiver or smartphone app, eliminating the need for frequent and invasive finger pricks. They are normally replaced every 7 to 14 days to ensure continuous and reliable monitoring. Less common but growing in popularity are implantable CGMs, which can be worn for up to 90 days.

Benefits of CGMs

One advantage of using a CGM is the continuous tracking, which provides a comprehensive view of glucose levels. This can help people with diabetes better understand how their bodies respond to food, physical activity, and medication. It can also help them identify patterns and trends that may go unnoticed with blood glucose meter monitoring.

CGMs also help reduce the risk of low blood glucose (hypoglycaemia) and high blood glucose (hyperglycaemia) by providing real-time alerts when glucose levels are out of range. These alerts allow for timely intervention and prevent dangerous glucose level fluctuations. This added layer of safety can provide a sense of reassurance that supports mental well-being, which can be especially helpful for carers, parents of children with diabetes or people living alone.

CGMs also help make glucose monitoring more seamless and hassle-free by eliminating the need to perform frequent finger pricks throughout the day.

Drawbacks of CGMs

Unlike blood glucose monitors, CGMs measure glucose levels from the fluid in the spaces around cells, known as interstitial fluid. In contrast to finger-prick testing, which provides immediate results, with CGMs there is a delay of five to 15 minutes in reporting changes in glucose levels. This can cause differences in readings and how a person feels.

The constant monitoring and stream of data associated with CGMs can exacerbate diabetes-related stress and cause anxiety and decision paralysis, increasing the emotional burden for people with diabetes. Other factors that can disrupt the seamless use of CGMs include:

• Sensor adhesion issues, particularly when doing a physical or outdoor activity.
• Connectivity problems and software glitches.
• Compatibility requirements with certain smartphones or need of additional equipment for data synchronisation.
• Inaccurate readings that can lead to potential misinterpretation and incorrect treatment decisions.

For healthcare professionals, CGM data can be complex to understand and use effectively, requiring specialised knowledge and training. Furthermore, integrating CGM data analysis into routine patient consultations can be time-consuming, impacting the overall efficiency of healthcare delivery.

Barriers to accessing CGMs

Although CGMs have revolutionised diabetes management, barriers exist to accessing this technology, particularly in low- and middle-income countries (LMICs). In higher-income settings, insurance coverage can limit access to CGMs and related supplies, leading to financial barriers for people with diabetes and healthcare facilities.

In LMICs, the affordability of devices and healthcare infrastructure challenges limit access to CGM technology. These constraints are compounded by healthcare professionals’ need for specialised training and resources to support people with diabetes in effectively using CGMs.

Diabetes education can play a crucial role in addressing and overcoming the challenges faced by people with diabetes and healthcare professionals in accessing and using CGM technology, particularly in LMICs.