A continuous glucose monitor (CGM) is a medical device that tracks glucose levels throughout the day. The CGM is inserted under the skin, usually in the abdomen or in the upper arm. The sensors of the device then measure the glucose levels of the fluid between the cells (interstitial glucose levels). The transmitter on the sensor then send the glucose level readings to a monitor that can be clipped on to your clothes or worn on your wrist. The CGM measures and displays glucose levels every 5, 10, or 15 minutes. An inbuilt alarm is triggered if the sugar levels fall dangerously low or become too high. The advantage of a CGM device is that it records glucose levels throughout the day allowing for easy understanding and graphical views of your round-the-clock blood glucose levels.
Before you decide to opt for a CGM, it is important that you consult your diabetologist and also understand the facts behind the various myths about CGM
Myth 1 – I do not need a finger stick test with a glucometer if I use a CGM
Fact – The CGM cannot completely replace the use of a glucometer. The CGM checks the glucose levels of the interstitial fluid and this may vary slightly from the blood glucose levels. Besides, the CGM needs to be calibrated from time to time. This can only be done vis-a-vis the readings obtained by finger stick tests.
Myth 2 – CGM devices are only needed if you need to know blood glucose levels throughout the day
Fact – It is true that the CGM device provides blood glucose readings every few minutes. This is definitely needed in case of patients who experience extreme fluctuations of sugar levels. CGM is also essential to present the treating physician with a bird’s eye view of the blood sugar fluctuations through the day and across a period of time. This helps in calibrating the medication.
Myth 3 – CGM devices are not accurate
Fact – Your CGM device reading may vary slightly from the reading of your glucometer. This is because the glucose levels tested by the glucometer are from the blood while that of the CGM device is from the interstitial fluid. The variance is a small one and is to be expected. This does not mean that the CGM is inaccurate.
Myth 4 – CGM cannot help in case of a hyperglycaemic episode.
Fact – Some CGM devices come with an inbuilt insulin pump. This means that they prevent the blood sugar levels from going very high and causing a spike in the a1C levels. All CGM, however, do not come with insulin supply mechanisms. It is best to discuss the specific device you are using with your doctor. All CGM devices sound an alert when the sugar levels fluctuate and reach dangerous levels.
Myth 5 – CGM readings are difficult to decipher.
Fact – The CGM monitor is similar to a smartphone and is very easy to read. The readings are also recorded and displayed in a simple graphical format. Your doctor or hospital may also be connected to the CGM readings and may remotely monitor your glucose levels.