· CDE Mehandi Sharma
What Is Time in Range?
Time in range is the percentage of the day your glucose spends between 70 and 180 mg/dL. It comes from continuous glucose monitoring, and it answers a question HbA1c cannot.
HbA1c gives you one average for three months. Two people with an identical HbA1c of 7.5% can have completely different days — one steady, the other swinging between 50 and 300 mg/dL. Time in range separates them.
| Measure | Target |
|---|---|
| Time in range (70–180 mg/dL) | More than 70% of the day |
| Time above 180 mg/dL | Less than 25% |
| Time below 70 mg/dL | Less than 4% |
| Time below 54 mg/dL | Less than 1% |
Seventy per cent of a day is roughly 17 hours. That is the target for most adults — but not for everyone. For older or more fragile people, where a low is the greater danger, the consensus sets a gentler goal: more than 50% in range, with under 1% spent below 70 mg/dL. In pregnancy the range itself tightens to 63–140 mg/dL.
The two measures track each other closely: across studies, every 10% change in time in range corresponds to roughly a 0.8% change in HbA1c. Time in range is not a replacement — it is the detail behind the average.
You need a CGM to measure it properly. Finger-prick readings cannot tell you what happened between them, which is exactly where this number lives.