Time in range is a continuous glucose monitor metric that shows the percentage of time your glucose is within a target range. For many adults with diabetes, a common CGM range is 70 to 180 mg/dL, or 3.9 to 10 mmol/L, but personal targets may differ.
Quick summary
Time in range can add useful context to A1C because it shows highs, lows, and daily patterns. It should be interpreted with your diabetes care team, not used as a reason to make medication changes on your own.
Key takeaways
- Time in range is usually reported as a percentage over days or weeks.
- A higher time in range is helpful only if time below range stays low.
- Targets may be different for pregnancy, older adults, children, high hypoglycemia risk, or serious illness.
- CGM readings are useful but can lag behind blood glucose, especially during fast changes.
Why it matters
A1C gives an average over about three months, but it does not show whether glucose is swinging high and low. Time in range helps reveal how often glucose is in the target zone, how often it is high, and how often it is low.
The 2019 international consensus report helped standardize CGM metrics, including time in range, time below range, and time above range. ADA guidance continues to support CGM metrics as part of diabetes care when CGM is used.
Common CGM terms
- Time in range: percent of readings within the agreed target range.
- Time below range: percent of readings below target, especially below 70 mg/dL or 3.9 mmol/L.
- Time above range: percent of readings above target.
- Glucose management indicator: an estimate based on CGM data, not the same thing as a lab A1C.
- Ambulatory glucose profile: a summary report showing repeated daily patterns.
How to use it wisely
Look for repeated patterns, such as overnight lows, breakfast spikes, exercise-related drops, or late evening highs. A single unusual day may reflect illness, stress, a sensor issue, missed medication, a meal, or exercise.
The safest first step is often observation: confirm symptoms, check device accuracy when needed, note the pattern, and bring the report to your care team.
Practical takeaway
Use time in range as a pattern tool. The goal is not a perfect score. The goal is safer, steadier glucose with fewer lows and fewer prolonged highs.
Safety note
If CGM symptoms do not match how you feel, follow device instructions and confirm with a finger stick if advised. Seek urgent help for severe low blood sugar, confusion, ketones, vomiting, or signs of DKA.
Related Livingdiabetes guides
Sources
- CGM and Time in Range, American Diabetes Association. Patient guidance. Accessed May 30, 2026. Source
- Clinical Targets for Continuous Glucose Monitoring Data Interpretation, Diabetes Care. International consensus report. Accessed May 30, 2026. Source
- Diabetes Technology: Standards of Care in Diabetes 2026, American Diabetes Association. Guideline. Accessed May 30, 2026. Source
- Continuous Glucose Monitoring, National Institute of Diabetes and Digestive and Kidney Diseases. Patient guidance. Accessed May 30, 2026. Source
- Continuous Glucose Monitors, Centers for Disease Control and Prevention. Patient guidance. Accessed May 30, 2026. Source