To monitor your blood sugar (glucose) concentrations; to evaluate changes and trends in your glucose concentration over time
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.
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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.
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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.
CGM may be used when you have diabetes and hypoglycemia unawareness (no distinct symptoms) and/or frequent low or high blood glucose.
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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.
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Can I buy a CGM device over-the-counter?
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Can I use a device for longer than indicated?
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Is there anything else I should know?