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Diabetes and continuous glucose monitoring

A continuous glucose monitoring (CGM) system for people with type 1 diabetes is a system to record blood sugar levels around the clock using a sensor placed under the skin, usually in the abdomen.

The sensor stays in for several days up to a week. The devices are more expensive than traditional glucose test meters, and may not be available from the NHS. However, the National Institute for Health and Care Excellence (NICE) says there is evidence they can help improve glucose control and avoid hypos in adults and children.

How does the device work for diabetes?

There are a number of differences in the way that the different devices for continual glucose monitoring are used. The insertion is quick, and is usually not painful. It's very similar to insertion of an insulin pump catheter. Tape is used to hold it in place.

The sensor measures the level of glucose in the tissue every 10 seconds and sends the information via a wire to a small monitor attached to a belt or the waistband of your clothes. The system automatically records an average glucose value every five minutes for up to 72 hours.

Results of at least four finger stick blood sugar readings taken with a standard glucose meter and taken at different times each day are entered into the monitor for calibration. Any insulin taken, exercise engaged in, and meals or snacks consumed are entered into a paper-based diary and recorded into the monitor - by pushing a button to mark the time of the meals, medication, exercise, and other special event you wish to record.

After 3 days, the sensor is removed at the doctor's surgery and the information stored in the CGM is downloaded into a computer. You and your doctor or diabetes health care team can then review your blood sugar levels in relation to the other data collected and make any necessary adjustments in your diabetes management plan. The information will be presented as graphs or charts that can help reveal patterns of glucose fluctuations.

When is the continuous glucose monitor used?

The continuous glucose monitor is not intended for day-to-day monitoring or long-term self-care and it is not a replacement for standard blood sugar monitoring. It is primarily intended for use to discover trends in glucose levels. This helps your health care team make the most appropriate recommendations regarding your treatment plan.

The main advantage of continuous glucose monitoring is that it can help identify fluctuations and trends that would otherwise go unnoticed with standard HbA1c tests and intermittent finger prick measurements.

For example, the device can capture dangerously low overnight blood sugar levels which often go undetected, reveal high blood sugar levels between meals, show early morning spikes in blood sugar, evaluate how diet and exercise affect blood sugars, and provide up to a 72-hour complete review of the effects of changes made to your therapy by your health care team.

Your doctor can recommend the procedure as often as he or she believes it necessary to appropriately evaluate your blood sugar patterns. Check with your doctor to see if you might benefit from continuous glucose monitoring.

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WebMD Medical Reference

Medically Reviewed by Dr Rob Hicks on January 11, 2018

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