Continuous Glucose Monitoring
NHS funding for CGM is restricted to people with difficult to manage diabetes mellitus. Short term use may be available from a clinic if they own a device for short term use to help guide insulin therapy. Long term use is restricted to specific individuals as per NICE guidance. For adults this primarily involves difficulty with low blood glucose (hypoglycemia), or high despite testing by finger prick at least 10 times a day. For children the rules are slightly less restrictive. The purpose of CGM is to help the patient and team control blood sugars better and avoid too many finger prick tests.
A continuous glucose monitoring (CGM) device includes a small sensor wire that is inserted beneath the skin of the abdomen or the upper arm and held in place with an adhesive patch. The sensor measures glucose in the space around cells (interstitial space). CGM measures glucose at frequent intervals and sends the results wirelessly to a device that is attached to your clothing or in some cases to a smart phone. These digital readouts let you know your equivalent blood glucose level in real time.
No test preparation is required.
Continuous glucose monitoring (CGM) measures the glucose in the space surrounding cells (interstitial space). Blood, including finger prick, and interstitial fluid glucose levels are not exactly the same, but they mirror each other closely.
Some features of CGM devices include:
- A small sensor wire that is inserted beneath the skin of the abdomen or the upper arm and then held in place by a sticky patch for several days (7, 10, or 14) up to 3 months.
- A transmitter above it on top of the skin. A device to show the results, which may be a smart phone, pump or separate hand held machine.
- the information can be used in several ways.
- CGM devices can measure and display glucose readings "real-time" at set intervals, or display the last glucose result performed when they are scanned (intermittent scanning or flash).
- CGM devices may send alerts and have alarms.
One use of CGM is in conjunction with an insulin pump. When you eat and your glucose level rises, your CGM device measures glucose levels. Controls in the insulin pump react to this result to deliver insulin.
How is it used?
CGM is not used by a majority of people with type 1 diabetes, but as CGM devices become increasingly accurate and user-friendly, their use is increasing.
National Institute for Health and Care Excellence (NICE) recommend CGM for a limited number of reasons:
Children and young people with type 1 diabetes who have frequent severe hypoglycaemia are offered ongoing real time continuous glucose monitoring with alarms.Adults with type 1 diabetes and episodes of disabling hypoglycaemia despite optimal management with continuous subcutaneous insulin infusion.
When is it requested?
Real-time CGM may be used daily and constantly to have better glucose control when you have type 1 diabetes.
CGM may be used periodically when you have diabetes and your healthcare practitioner wants to collect and evaluate data on your day-to-day glucose variability and control.
What does the test result mean?
Glucose values from CGM devices generally correlate closely with blood glucose concentrations. Your target range for your glucose levels is determined by your healthcare professional and depends on several factors, such as:
- How long you have had diabetes
- Your age and life expectancy
- Other underlying conditions you may have, including heart disease
- Whether you do not experience distinct symptoms of low blood sugar (hypoglycemia unawareness)
CGM results can identify variability in glucose levels throughout the day, identify trends and anticipate when your glucose level is getting too low (hypoglycemia) or too high (hyperglycemia), sending an alert.
Looking at patterns of glucose data (such as data points collected over several days and graphed in a report) can help you and your healthcare practitioner evaluate variations in your glucose levels and suggest actions that may help stabilise glucose levels and improve glucose control.
Can I buy a CGM device over-the-counter?
Can I use a device for longer than indicated?
Is there anything else I should know?
Elsewhere On The Web
NHS: Continuous glucose monitoring (CGMs)
Diabetes UK: Continuous glucose monitoring (CGM)
Diabetes UK: Living with a continuous glucose monitor
JDRF: Continuous glucose monitors (CGM)
Children with Diabetes UK