Continuous Glucose Monitoring (CGM)
The cornerstone of managing type 1 diabetes (T1D) has evolved from urine glucose testing (I had test tubes when I was diagnosed!) to now using accurate, timely blood glucose data. Traditional finger-prick testing gives only isolated snapshots. Continuous glucose monitoring (CGM) changes that, providing a dynamic, real-time picture of glucose trends and patterns. This technology empowers people with T1D to make more informed decisions, reduces the risk of hypoglycaemia, and improves overall quality of life.
Pharmac funding
On October 1st 2024 Pharmac (the New Zealand Pharmaceutical Management Agency) announced that certain Continuous Glucose Monitors (CGMs) and Insulin Pumps would be funded for eligible people living with Type 1 diabetes and certain other insulin-dependent types of diabetes. This was a landmark decision with significant impact for everyone living and working in the diabetes space in Aotearoa New Zealand.
You can find out more from the Pharmac website here.
What is Continuous Glucose Monitoring?
CGM systems use a small sensor inserted under the skin (typically on the abdomen or upper arm) to measure glucose levels in the interstitial fluid every few minutes. These readings are transmitted to a receiver, smartphone app, or insulin pump, providing near-continuous feedback. Most systems also offer trend arrows and alarms for high and low glucose.
There are two main types of CGM*:
- Real-Time CGM (rtCGM): Continuously transmits data to a device or app.
- Intermittently Scanned CGM (isCGM): Records glucose levels continuously, but requires the user to scan the sensor to view data.
*At the time of this update isCGMs have now been superseded by newer models that use Bluetooth and don’t need to be scanned
Key Features and Benefits
- Trend Data: Instead of isolated points, CGM shows whether glucose is rising, falling, or stable, allowing proactive adjustments.
- Alerts and Alarms: Warn users of impending hypo- or hyperglycaemia — including overnight, when finger-prick checks are rare.
- Data Sharing: Caregivers or healthcare teams can remotely access glucose data, improving collaborative care.
- Time in Range (TIR): CGM enables a new metric beyond HbA1c — the percentage of time glucose remains within the target range — offering a more nuanced picture of control.
Impact on Diabetes Management
Research consistently shows CGM use in people with T1D leads to:
- Lower HbA1c levels.
- Reduced incidence and duration of hypoglycaemia.
- Improved treatment satisfaction and quality of life.
CGM is particularly helpful for children, older adults, pregnant people, and anyone experiencing frequent hypo- or hyperglycaemia.
Challenges and Considerations
Despite its advantages, CGM also has limitations:
- Cost and Access: Devices can be expensive, and coverage varies by country and insurer.
- Calibration: Some systems still require occasional finger-prick calibration.
- Learning Curve: Users and healthcare professionals need training to interpret and act on CGM data effectively.
- Sensor Life and Adhesion: Sensors typically last 7–14 days and may occasionally dislodge.
A Stepping Stone to Automated Insulin Delivery
CGM is not only a monitoring tool but also the foundation of next-generation diabetes therapies. Hybrid closed-loop insulin pump systems — sometimes called “artificial pancreas” technology — use CGM data to automatically adjust insulin delivery. This reduces the burden of diabetes management even further and improves glucose control.
>> More on Automated Insulin Delivery (AID) systems
Continuous glucose monitoring marks a pivotal shift in how people with T1D understand and manage their glucose levels. By moving beyond snapshots to a continuous stream of actionable data, CGM empowers individuals, enhances safety, and lays the groundwork for the next leap in diabetes technology — hybrid closed-loop insulin pump systems.
Page updated: September 2025
