Where should I keep the receiver?
The CGM receiver needs to be within 5–8 feet of your body. You can put it in a pocket, clip it to your waistband, put it in your sock, or keep it in your purse or a bag that you carry with you. You can also keep it on a table or chair next to you, but don’t forget to take it with you when you get up. When you are in bed, you can either clip the receiver onto the waistband of your pajamas or underwear, keep it in the bed with you, or place it on a bedside table. Keep in mind that bedcovers can muffle sensor alarms, making them more difficult to hear. If you are relying on the alarm to wake you up in case of a low glucose level, the receiver should not be under the covers with you.
There is one major caveat, however: The signal from the CGM transmitter can only travel 5–8 feet in a direct line. It has great difficulty wrapping around the body: So, for example, if you put your sensor transmitter on your front and your receiver in a back pocket — or vice versa — the signal may not be successfully transmitted. Additionally, metal chairs and other devices or signals in the air may interfere with sensor signal transmission. Swimming with a sensor will also not give any data, since the transmitter cannot send a signal through water.
I find that the CGM system misses my low blood glucose.
There can be a lag time of 4–10 minutes between actual blood glucose and sensor glucose values, especially during times of rapid glucose fluctuation. There can also be up to 20% variability between the sensor glucose reading and the actual blood glucose level. To account for these limitations, you can set your low glucose target higher, so that the CGM catches your lows earlier. You can also use the predictive alert and the rate-of-change alert that exist on some CGM systems to help you identify when your glucose level is dropping quickly, so that you can intervene before it becomes too low. Remember that low glucose readings on the sensor should be confirmed by a fingerstick blood glucose check. CGM is more useful for following the trends in your glucose levels so that you can predict and prevent highs and lows than for giving you a precise reading at any one moment.
Patience pays off.
With a good understanding of both its benefits and its limitations, a CGM can serve you well in your diabetes care — and you don’t have to use it every day for the rest of your life for it to help. Even when used intermittently, such as for one to two weeks every month, a CGM can help to improve your blood glucose control.
If you are new to using a CGM, try it for at least three different sensors before giving up, and ask your CGM trainer and/or diabetes educator for guidance if you’re having trouble. In time, you too may become one of a growing number of people with diabetes who never want to stop using continuous glucose monitoring.