Your CGM can tell you how much of your day you spend “in-range.” But what exactly does that mean? And what kind of goals should you set around that information?
Time in range (TIR) is the amount of time you spend per day with blood sugar levels in your ideal range. Time below glucose target range (TBR) is the time you’ve spent with blood sugar lower than your ideal range. Time above glucose target range (TAR) is the time you’ve spent above it.
A main goal for safe and effective blood sugar management is to increase the TIR while lowering the TBR. However, if your TBR exceeds the recommended limit, your doctor may want you to focus on reducing lows first. Once you’ve addressed that, you can focus on lowering highs to improve your overall TIR.
Your CGM calculates TIR automatically. This information allows you to look back over a period of time and identify areas where your plan is working and where changes are needed. For instance, if there are certain mealtimes when your blood sugar is higher, try adjusting portion sizes or experimenting with different food choices. If you notice your blood sugar is more stable on days that you’ve exercised, add in another day of activity. This information gives you the power to do more of what is working for you and change what is not working.
Your TIR goals may vary depending on your age and risk for low blood sugar. Some adults older than age 65, as well as those with other conditions like kidney disease and heart disease, may be considered high risk and have different goals than others. Talk to your doctor about which category you fall into. In general, experts recommend the following TIR goals:
People With Diabetes (Type 1 or Type 2):
- TIR more than 70% of readings per day. This means being in range (4.0 -7.0 mmol/L) for about 17 hours in each 24-hour period.
- TBR less than 4% of readings per day. This means spending less than one hour below 4.0 mmol/L every 24 hours.
- Time spent in a very low range (less than 3.0 mmol/L) should be as close to zero as possible. This means less than 1% of readings, or no more than 15 minutes in any given 24-hour period in this range.
Older or High-Risk People With Diabetes (Type 1 or Type 2):
- TIR more than 50% of readings per day. This means at least 12 hours out of each 24-hour period.
- TBR less than 1% of each day. This means less than 15 minutes in any 24-hour period.
These goals do not apply to people who are pregnant. If you are pregnant, consult your doctor.