'Now Is the Time to Learn' About CGM

Anne L. Peters, MD


November 10, 2017

Today I have some updates about continuous glucose monitoring. Those of you who have seen my previous videos know how important I believe continuous glucose monitoring is for patients and providers. Until now, all of the continuous glucose monitors (CGMs) have required regular calibration. This means patients have to prick their fingers to calibrate the monitor two to three times a day, which is bothersome, but not that much considering all of the data you get from a CGM.

But now, the first ever factory-calibrated CGM has been approved by the US Food and Drug Administration (FDA) and should be available by the end of the year. This CGM has already been on the market in Europe. It is called the FreeStyle Libre, and it has even been available over-the-counter in some countries. This is pretty amazing—it's almost like wearing a Fitbit, except that it is a monitor to check blood sugar.

To me, this widens the application. It is simple and it replaces fingersticks. This is a plus not only for our type 1 diabetics who need a lot of monitoring, but also for type 2 diabetics who may need more episodic monitoring.

The Libre comes in a box comprising two pieces: the device that inserts the monofilament under the skin, and the sensor itself. The patient simply takes off the top, spring-loads the sensor into the loader, presses it against the skin, and boom—there is a loud click and the sensor is inserted. It sticks on the patient's arm and under the skin.

I am wearing one of these CGMs with a flat, white, round plastic piece that is stuck on my arm. In some cases, patients may sweat a lot and it may fall off, but you can put a bandage over it to maintain the seal. On me it sticks quite well. I can take a shower and it still stays on.

I do not have diabetes, but I have been wearing this monitor because I find it interesting to see the impact of food on my blood sugar levels. For people with diabetes, once they put this on they no longer have to prick their fingers, which is a game-changer for many of our patients.

A Few Caveats

The FDA is requiring a 12-hour warm-up period, which means that for the first 12 hours after the device is put on the arm, it cannot be used for blood glucose readings. This CGM will last for about 10 days before it stops working and has to be replaced with a new one.

The Libre is quite accurate and quite easy to wear. It has a very low profile. But it does not give patients an alert or an alarm when their blood sugars are going high or low.

To get a blood sugar reading, patients have to take the device reader and scan it by running it past the sensor. It backfills for the previous 8 hours so patients can see previous blood sugar levels. It also shows trend arrows, so it might say that the blood sugar is 100 mg/dL and is going up, for example. Consequently, a patient may do something different in terms of diet or exercise than if the blood sugar were trending downward.

The other sensors on the market, such as the Medtronic and DexCom sensors, not only sense the blood sugar levels, but they give patients alerts and alarms. They can warn people when their blood sugar levels are falling or when they are going up so the patient can do something about it.

In particular, these CGMs can alert patients at night, waking them up so that they do not go too low. These existing sensors obviously play a very important role, particularly in our patients with type 1 diabetes and any patient who is having issues with severe hypoglycemia.

With the Libre coming on the market and not needing to be calibrated, it opens the world to continuous glucose monitoring for people who may not have previously been interested in it, for people who do not want to do fingersticks, and also for us as providers to access more data from our patients.

Whether or not you are familiar with continuous glucose monitoring, I believe that now is the time to learn, because continuous glucose monitoring is here to stay. We are only getting more and better devices. It is important that you discuss with your patients what is possible for them, which CGM may be useful for them, and how to use it.

This is Dr Anne Peters for Medscape. Thank you.


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