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Time in range vs A1c
Time in range comes from a continuous glucose monitor (CGM) and A1c from a blood test. They are related, but not the same, and each shows something the other misses.
The short answer
- 70% time in range is about an A1c of 7%, and 50% is about 8% (Battelino 2019). The ADA notes that the goal of more than 70% aligns with an A1c of about 7% (ADA Standards 2026, sec. 6).
- Each 10% more time in range (2.4 hours a day) went with an A1c about 0.5% lower (Battelino 2019).
- Both count. The ADA says glycemic status can be assessed by A1c and/or CGM metrics such as time in range (ADA Standards 2026, sec. 6).
What time in range is
Time in range (TIR) is the share of CGM readings between 70 and 180 mg/dL (3.9 to 10.0 mmol/L). It is reported with time below range (hypoglycemia) and time above range (ADA Standards 2026, sec. 6). The ADA says a 10- to 14-day CGM assessment, with the sensor active at least 70% of the time, can be used to assess glycemic status (ADA Standards 2026, sec. 6).
Time in range to A1c chart
| Time in range | Estimated A1c | 95% range of predicted A1c |
|---|---|---|
| 20% | 9.4% (79 mmol/mol) | 8.0 to 10.7% |
| 30% | 8.9% (74 mmol/mol) | 7.6 to 10.2% |
| 40% | 8.4% (68 mmol/mol) | 7.1 to 9.7% |
| 50% | 7.9% (63 mmol/mol) | 6.6 to 9.2% |
| 60% | 7.4% (57 mmol/mol) | 6.1 to 8.8% |
| 70% | 7.0% (53 mmol/mol) | 5.6 to 8.3% |
| 80% | 6.5% (48 mmol/mol) | 5.2 to 7.8% |
| 90% | 6.0% (42 mmol/mol) | 4.7 to 7.3% |
From the International Consensus on Time in Range, Table 5, based on Beck et al.: 545 adults with type 1 diabetes in four trials (Battelino 2019).
Look at the last column. At 70% time in range, the predicted A1c spans about 5.6% to 8.3%, so the chart describes groups, not one person. A second analysis in the same consensus, of 18 trials with type 1 and type 2 diabetes, found a steeper link: about 0.8% A1c for each 10% of time in range (Battelino 2019). The ADA notes that time in range, and especially mean CGM glucose, correlates with A1c (ADA Standards 2026, sec. 6). Mean glucose is what the glucose management indicator (GMI) is calculated from (Bergenstal 2018).
CGM goals from the ADA
| Metric | Most adults | Older adults, complex or intermediate health |
|---|---|---|
| Time in range, 70 to 180 mg/dL (3.9 to 10.0 mmol/L) | More than 70% | More than 50% |
| Time below 70 mg/dL (3.9 mmol/L) | Less than 4% | Less than 1% |
| Time below 54 mg/dL (3.0 mmol/L) | Less than 1% | Less than 1% |
| Time above 180 mg/dL (10.0 mmol/L) | Less than 25% | Less than 50% |
| Time above 250 mg/dL (13.9 mmol/L) | Less than 5% | Less than 10% |
ADA Standards 2026, Table 6.2, nonpregnant adults with type 1 or type 2 diabetes, adapted from the international consensus (ADA Standards 2026, sec. 6) (Battelino 2019).
What each one misses
- A1c reflects average glucose over about 2 to 3 months, but gives no information on day-to-day highs, lows or swings (Battelino 2019). Conditions such as anemia, iron deficiency and pregnancy can also affect it; see when A1c can mislead.
- A1c is still the anchor. The consensus calls it the only prospectively evaluated tool for assessing the risk of diabetes complications, and says it is most useful alongside CGM data (Battelino 2019).
- Time in range needs a CGM worn most of the time over about 2 weeks (ADA Standards 2026, sec. 6), and covers a much shorter period than A1c.
For the A1c side, see A1c goals in diabetes and the GMI vs A1c chart.
Frequently asked questions
What A1c does 70% time in range equal?
About 7%. In data from 545 adults with type 1 diabetes, a time in range of 70% corresponded to an A1c of about 7% and 50% to about 8%. The ADA notes that the goal of more than 70% time in range aligns with an A1c of about 7%.
Is time in range better than A1c?
They answer different questions. A1c reflects about 3 months and is the measure linked to long-term complications in trials. Time in range shows daily highs and lows, including hypoglycemia, which A1c cannot show. The ADA says either can be used to assess glycemic status, and the consensus recommends using them together.
Can I convert my time in range to an exact A1c?
No. The match is an average across many people, with a wide range for any one person: at 70% time in range, the predicted A1c ranged from about 5.6% to 8.3%. Mean CGM glucose tracks A1c more closely, which is what the glucose management indicator (GMI) uses.
What is a good time in range?
For most nonpregnant adults with diabetes, the ADA goal is more than 70% of readings between 70 and 180 mg/dL, with less than 4% below 70 mg/dL. For older adults with complex or intermediate health, it is more than 50% in range and less than 1% below 70 mg/dL.
Sources
- American Diabetes Association Professional Practice Committee. 6. Glycemic Goals, Hypoglycemia, and Hyperglycemic Crises: Standards of Care in Diabetes 2026. Diabetes Care. 2026;49(Suppl 1). doi.org/10.2337/dc26-S006
- Battelino T, Danne T, Bergenstal RM, et al. Clinical targets for continuous glucose monitoring data interpretation: recommendations from the International Consensus on Time in Range. Diabetes Care. 2019;42(8):1593-1603. pmc.ncbi.nlm.nih.gov/articles/PMC6973648/
- Bergenstal RM, Beck RW, Close KL, et al. Glucose Management Indicator (GMI): a new term for estimating A1C from continuous glucose monitoring. Diabetes Care. 2018;41(11):2275-2280. doi.org/10.2337/dc18-1581
Written and maintained by the controla1clevels.com editorial team. We do not have a medical reviewer; every claim links to its primary source above. Last reviewed: 2026-10-28. Spotted an error? See About.