Time in range: what it is and how it is calculated
Time in range is the percentage of the day your glucose stays between 70 and 180 mg/dL (3.9 to 10.0 mmol/L), usually measured with a continuous glucose monitor. An international consensus suggests most non-pregnant adults with type 1 or type 2 diabetes aim for more than 70% of the day in range, but your own target is set with your care team.
How is time in range calculated?
Take all the glucose readings in a period, count how many fall between the lower and upper limit, and divide by the total. A sensor records a reading every few minutes, so two weeks of data holds thousands of readings. The standard range is 70 to 180 mg/dL (3.9 to 10.0 mmol/L).
Example: if 700 of 1,000 readings are between 70 and 180 mg/dL, your time in range is 70%.
What does the international consensus recommend?
An international panel published targets for continuous glucose monitoring in Diabetes Care in 2019. For most non-pregnant adults with type 1 or type 2 diabetes:
| Range | Glucose | Share of time |
|---|---|---|
| Time in range | 70 to 180 mg/dL (3.9 to 10.0 mmol/L) | More than 70% |
| Time below range | Below 70 mg/dL (3.9 mmol/L) | Less than 4% |
| Time well below range | Below 54 mg/dL (3.0 mmol/L) | Less than 1% |
| Time above range | Above 180 mg/dL (10.0 mmol/L) | Less than 25% |
The same consensus gives different targets for pregnancy and for older or higher-risk adults. Your care team may also set personal targets.
Why look at time in range as well as A1c?
Two people can have the same A1c with very different days: one steady, the other with large highs and lows. Time in range shows that difference. Many care teams look at both.
How much data is needed?
Reports based on a sensor usually use at least 14 days of data. Fewer days give a less reliable picture.
Try it with your own readings
The average glucose and time in range calculator works out the share of your readings below, in and above a range you choose. It runs in your browser.
Information, not medical advice. Talk to your care team about your own targets and treatment. Never use a converter or a diary entry to work out an insulin or medicine dose.
Sources
- Battelino et al., Diabetes Care, 2019: Clinical targets for continuous glucose monitoring data interpretation
- Bergenstal et al., Diabetes Care, 2018: Glucose Management Indicator (GMI)
Frequently asked questions
Is time in range the same as A1c?
No. A1c is an average over about three months. Time in range shows how much of the day your glucose spent inside a range, so it also shows highs and lows that an average can hide.
Can I work out time in range from finger-stick readings?
Only roughly. Finger-stick readings are a few moments in a day, while a sensor records every few minutes. The calculator on this site gives the share of your entered readings that fall in range.
Do the same targets apply in pregnancy or for older adults?
No. The consensus gives different targets for pregnancy and for older or higher-risk adults. Ask your care team which ones apply to you.
Keep reading
Average glucose calculator
Paste your glucose readings to see the average, highest, lowest, time below, in and above range, variability and GMI. Free and private, in your browser.
Blood sugar basicsGMI explained
The glucose management indicator (GMI) estimates A1c from the average glucose on a CGM. The formula, a table and why it can differ from your lab A1c.
Blood sugar basicsA1c vs daily readings
How A1c differs from daily blood sugar readings, what estimated average glucose (eAG) means, and why the two numbers do not always match.