Understanding your CGM data

One of the benefits of your continuous glucose monitor (CGM) is how much data it provides. However, having so much information can also feel overwhelming. 

You may also notice that data from your CGM is different from that of your blood glucose monitor (BGM). Blood glucose monitors measure the amount of glucose in your blood, while CGMs measure the glucose in the fluid just under your skin. When your glucose levels change, it’s reflected in your blood immediately. The fluid under your skin reflects the change 5 to 20 minutes later.

Your blood glucose meter is great at telling you where your glucose levels are now—in real time. However, your CGM can look back and give you a more detailed overview of where your glucose levels have been.

Understanding the key metrics that your CGM gathers can help you make the most of it. The goals below are based on general clinical guidance; talk to your provider about what’s right for you.

Time in range (TIR)

The amount of time a person spends in their target glucose goal range. For most people with diabetes, the goal range is 70 to180 mg/dL. TIR reflects the percentage of total readings that are in range.  

Typical goal: Above 70%

What it looks like: Staying at a TIR above 70% means that over the past 24 hours, you’ve been in range for at least 17. 

Time above range (TAR) 

The amount of time a person spends over the high end of their target glucose goal range. For most people with diabetes, this will be 181 mg/dL and above. TAR is measured as a percentage. 

Typical goal: Less than 25%

What it looks like: Staying at a TAR of less than 25% means you’ve been above the target range for less than 6 hours over the past 24 hours. 

Time below range (TBR)

The amount of time a person spends below the low end of their target glucose goal range. For most people with diabetes, this will be less than 70 mg/dL. TBR is measured as a percentage. 

Typical goal: Less than 4%

What it looks like: Staying within a TBR of less than 4% means you’ve been below range for less than 1 hour out of the past 24 hours. 

Estimated average blood glucose (eAG)

The average glucose level over a given time period. Your eAG can directly correlate to your A1c level.  

Typical goal: <154 mg/dL

Glucose management index (GMI)

A metric that estimates a person’s A1c based on their average glucose levels. It is not a direct replacement for getting regular A1c levels from your doctor. 

Typical goal: Less than 7.0%

Please note: Your CGM data in the Teladoc Health app is delayed by at least one hour. This is due to the way the data is shared with us from the CGM company. Always use your CGM’s own app when making treatment decisions like taking medicine or treating low glucose levels. Your Teladoc Health app will tell you the last time your data has synced.

The data from your CGM can help make it easier to manage diabetes. If you’d like to know more about how CGM data can benefit you, connect with a coach.