If you use a continuous glucose monitor, you may have noticed a number called Time in Range, or TIR. Unlike a single glucose reading, Time in Range summarizes how much of your day your sensor readings spend within a defined glucose range.
For many nonpregnant adults with diabetes, the standard CGM target range is 70–180 mg/dL (3.9–10.0 mmol/L). The American Diabetes Association's 2026 Standards of Care state that a Time in Range goal above 70% is appropriate for many nonpregnant adults—but that glycemic targets should always be individualized.1
That last point matters: 70% is not a universal pass/fail score.
What Time in Range actually tells you
Suppose your CGM report says your Time in Range is 65%. That means approximately 65% of the CGM readings included in the report fell between 70 and 180 mg/dL, or 3.9 and 10.0 mmol/L.
A complete CGM picture includes more than TIR. You may also see Time Above Range (TAR) and Time Below Range (TBR). For many nonpregnant adults, the ADA's general CGM goals include more than 70% between 70 and 180 mg/dL, less than 4% below 70 mg/dL, and less than 1% below 54 mg/dL. Different goals may be appropriate for older adults, people at greater risk from hypoglycemia, or people with other health circumstances.1
That is why increasing TIR should never come at the expense of creating dangerous lows.
How Time in Range differs from A1C
A1C and Time in Range answer related but different questions.
A1C is a laboratory measurement that reflects average glycemic exposure over roughly the previous few months. Time in Range comes from CGM data and describes how glucose behaved during the period captured by the sensor.
Two people can therefore have similar average glucose or A1C values while experiencing very different daily patterns. One person's glucose might stay relatively steady. Another person's may alternate between pronounced highs and lows. CGM metrics can make that variability easier to see.
The ADA recognizes both A1C and CGM-derived measures as ways to assess glycemic status and emphasizes individualized goals rather than interpreting one metric in isolation.1
You may also see a Glucose Management Indicator (GMI) on a CGM report. GMI is calculated from sensor glucose data and provides an estimate related to A1C, but it is not simply another laboratory A1C result; the ADA specifically notes that GMI and A1C are not always equivalent.1
Look at where the out-of-range time occurs
Knowing that your TIR is 65% is useful. Knowing when the remaining 35% occurs may be even more actionable.
Perhaps glucose rises mainly after your evening meal. Perhaps the biggest change occurs early in the morning. Maybe Time Below Range clusters after a particular kind of physical activity. Or perhaps weekdays and weekends look noticeably different.
Those patterns give you and your health-care team something concrete to discuss.
A standardized CGM report covering an adequate period can be particularly useful for this type of pattern review. ADA guidance describes at least 14 days of CGM wear with sufficient active data as useful for pattern management and supports standardized reporting so people and their clinicians can assess the same core metrics.1
Do not let a percentage become a grade
It is easy to turn TIR into a daily score: 78% feels like success; 58% feels like failure. But diabetes does not work that way.
Illness, medication changes, sleep, stress, meals, activity, hormonal changes, travel, device issues, and many other variables may affect a CGM trace. A percentage is information, not a judgment about your effort.
A better question is: What does this pattern teach us?
If your Time Below Range is increasing, that may deserve attention even if your overall TIR looks “better.” If your TIR has gradually improved without problematic lows, that trend may be more meaningful than whether you hit a particular number every day.
Bring the metric back to your goals
At your next diabetes appointment, consider discussing three things: your usual Time in Range, when most of your Time Above or Below Range occurs, and whether your current target is appropriate for you.
Shared goal-setting matters. The ADA's 2026 guidance explicitly recommends setting individualized glycemic goals during clinical consultations and reassessing them when health, treatment burden, hypoglycemia risk, or other circumstances change.1
CGM creates an enormous amount of data. Time in Range is useful because it turns some of that complexity into a metric people can understand—but its greatest value comes when it leads to a better conversation rather than a more stressful one.
This article provides general education and does not establish individual glucose targets or replace advice from your diabetes care team.