The Value of Alerts:

Minimizing the DURATION and MAGNITUDE of Blood Glucose Excursions

Let’s look at a the difference continuous glucose monitors can make when making adjustments for blood glucose excursions.

This graphic shows the difference in response times for out-of-range excursions. With CGM alerts we get swift notifications and can take decisive actions on both hyper and hypoglycemic episodes, greatly reducing the time out-of-range, and the symptoms that can greatly impact quality of life.

Without these alerts we are largely dependent on the symptoms of excursions to signal us to check our blood sugar--and these delays lead to much more time out-of-range, as well as needing much larger treatments to correct.

Timely, Consistent Response is the Key to Success

Educating patients on what appropriate actions to take upon getting alerts, and on a timely basis, is the key to success.

And alerts should be points of action, not simply noises that happen when we “mess up”. The alerts should always be viewed as helpful and welcome, otherwise the patient may ignore them rather than reacting to them, to the point that alerts that are important to safety will be more likely to be over-looked as well.

Can the Numbers be Trusted?

So, this is the most important question.

There is a line in diabetes education that says 81% of CGM users admit to using values to dose, and 19% of users lie about it. The takeaway, for our purposes, is that if the CGM information is going to be used for dosing it needs to be accurate.

Depending on the CGM system being used there are some times that values are not going to be accurate enough for dosing. Regarding the use of CGM information to make dosing decisions:

It should not be used during first 1-2 sensor cycles: circulation of fluid around a new sensor needs time to stabilize.

It should not be used during the first 12-24 hrs after insertion: sensor variability or errors are most likely to change in the initial use period.

It should not to be used when recovering from hypoglycemia: sensor values tend to read artificially low for up to 45 minutes following treatment of a hypoglycemic episode.

It should not be used in a state of rapid rise or fall: the delay of accuracy between blood and interstitial fluid creates a delay that expands faster as blood sugars are changing.

It should not be used if recent the most calibration was off >20%: a CGM should be shown to be accurate before being trusted after a calibration.

It should not be used if acetaminophen has been taken in past 4 hrs: some CGMs are made inaccurate after using acetaminophen.