Continuous and Flash Glucose Monitoring

What and where do continuous glucose monitoring systems measure?

Measures glucose concentrations in the interstitial fluid.

What are the 2 types of CGMs?

• “real time”

• “blinded”

What is a “real time” CGM?

Provides information directly to the user, displaying moment-to-moment glucose levels and trending arrows, provides alarm notifications if ± target range. (aka Personal CGM)

What is a “blinded” CGM?

Captures but does not display the glucose readings, which are then downloaded for retrospective analysis by healthcare provider. (aka blinded CGM).

Benefits of CGM

• easy to scan

• increased glucose testing

• A1C reduction

• less variability in glycemic levels (more data → better understanding)

• more confidence to prevent hypo

• less time in hypo

• increased patient engagement and QoL

What is the Dexcom G7 CGM system?

• first fully mobile CGM system that send glucose data directly to compatible smart device

• data is transmitted every 5 minutes

  • allows for real time diabetes management

• approved for as young as 2 years old

What is Flash Blood Glucose Monitoring?

• Measures glucose in interstitial fluid

• is a “pull data” meter/sensor

  • the patient must scan the sensor in order to “pull the glucose data forward” to be seen

• older freestyle had no alarms, but newer ones will alert if outside target glucose range

  • still need to scan to pull the actual glucose number

What is the issue of measuring glucose in interstitial fluid?

Has a time delay of about 10-15 minutes.

Freestyle Libre 2 vs Dexcom G7

Freestyle	Dexcom
Pull Data	Push Data
14 day sensor	10 day sensor
wear on arm	wear several areas
1 hour warm up	30 minute warm up
Glucose every 1 minutes, but the average number every 15 min if not flashed	glucose sent every 5 minutes
	Can be used in pregnancy

What is the correlation between scan rate and A1C?

The more a patient scanned the more A1C dropped.

Who should NOT use a Flash or CGM?

• critically ill patients (where there are dramatic and quick changing BG)

  • reading may be inaccurate

• Dialysis

  • not tested in this population (but many still use)

• Implants medical devices, like pacemakers

  • not been evaluated yet

• severe dehydration or excessive water

  • may cause inaccurate results

What are some interfering substances for Freestyle?

• Ascorbic Acid

  • may falsely raise glucose reading

• Salicylic Acid

  • may slightly lower sensor readings

  • okay to use if 81mg ASA

How often do you need to scan a freestyle sensor?

• every 8 hours - b/c that is all the amount of data it can hold

• if miss scanning, will just have a blank 8 hour period

When to perform CBGM readings?

• In times of rapidly changing glucose levels

• suspect reading may be inaccurate

• experiencing symptoms of low or high

• experiencing symptoms that do not match sensor reading

• during first 12h

What is the minimum % time sensor is active?

Want at least active 70% of time for validity. To increase chance, encourage scanning at least 4x per day.

What percent in target should a patient be?

Aim to be in target 70% of the time, correlates to A1C <7.

What to review with CGM data?

DATAA

• download data

• assess safety

• time in range

• areas for improvement

• action plan

How to interpret the AGP report?

• look for lows first

• when are they in and out of target

• does the median curve go up and down drastically

• what is the variability among percentiles

• connections to be made with meals/exercise