Advice for use of glucose monitors (CGM) / sensor during radiotherapy

This leaflet outlines our advice for anyone receiving radiotherapy and who routinely wears a Continuous Glucose Monitor. This is to make sure you avoid any diabetic complications, as cancer treatment may affect your normal blood glucose levels.

View or download this resource as a PDF

Manufacturers and diabetes specialists recommend removing your CGM as radiotherapy may make readings inaccurate or interfere with how they work.

Please note: This advice excludes patients wearing hybrid close loop insulin pumps. Please contact your local Diabetes team for advice if you have a hybrid close loop pump.

Why might radiotherapy affect Continuous Glucose Monitors (CGM) / sensor?

CGMs are a relatively new technology. There is little information about the risk of high energy x-rays (radiotherapy) damaging the sensor and causing inaccurate readings. The advice is different to other scans as radiotherapy uses much stronger x-rays.

Why am I being asked to remove my CGM / sensor during radiotherapy?

Most manufacturers advise removing CGMs during radiotherapy. We therefore advise that you remove your device for the duration of your treatment. Please use capillary (finger prick) testing to monitor your blood glucose levels.

On finishing radiotherapy, you can return to using your CGM again.

What if I decide not to remove my CGM?

A decision not to remove a CGM during a course of radiotherapy would be against medical advice.

If you decide not to remove your device, we strongly recommend that you:

Use finger prick measurements regularly to check (calibrate) your sensor readings.
Be very vigilant of symptoms of high or low blood glucose levels.
Seek medical advice if there are any concerns regarding control of your diabetes.

We understand that removing your device may be inconvenient for you and the management of your diabetes. If you would like any further information or advice, please contact your local diabetes team.