You may have heard people mention time in range, or TIR, when talking about tracking type 1 diabetes (T1D).
When using a continuous glucose monitor (CGM), your time in range can be being used as another tool to check your glucose management over a longer period of time. CGMs can track the amount of time your blood glucose levels have been in your target range, and the times you’ve been high or low. This is all recorded as your time in range.
Time in range versus HbA1c
While it’s important to have your HbA1c tested several times a year, it doesn’t show how often your blood glucose levels have been too high or too low.
You can have an HbA1c of 7% (53mmol/ mol) with your glucose levels ranging from 4-10mmol/L; you can also have an HbA1c of 7% with your glucose levels ranging from 2-22mmol/L.
Your glucose levels in the last month will also contribute more to the HbA1c results than your glucose levels 2 to 3 months ago, which can cause a higher HbA1c.
Conditions like pregnancy and anaemia can also impact your result.
Your target time in range
Most diabetes experts agree that the ideal target range is 3.9-10.0mmol/L. There may be times when you’d want to have more of your glucose levels in this range, such as during pregnancy. There may also be times when it’s safer to have higher glucose levels – for example, if you’re having trouble recognising low blood glucose levels.
Overall, it’s generally recommended that most people aim for:
- 70% of their glucose levels to be in range (3.9-10.0mmol/L)
- less than 4% of their levels to be lower than 3.9mmol/L
- less than 1% of their levels to be below 3mmol/L. As a rule of thumb, a TIR of 70% usually matches with an HbA1c of 7% (53mmol/mol).
The more time you spend in range, the lower your chance of developing certain diabetes complications.
TIP: When it comes to your time in range, small changes can have big results. Every 10% improvement in TIR usually results in a 0.5mmol/L drop in HbA1c.
Learn more about time in range with Diabetes Australia.
