For decades, the A1C test has been the gold standard for evaluating diabetes management. It provides an important snapshot of average blood sugar levels over the previous two to three months and remains a valuable tool for diagnosing and monitoring diabetes.
However, thanks to advances in Continuous Glucose Monitoring (CGM), people with diabetes and their healthcare providers now have access to a much more complete picture of glucose control. One of the most meaningful metrics that CGM provides is Time in Range (TIR).
So, which measurement matters more: A1C or Time in Range? The answer is that both have value, but they tell very different stories.
At Sol Endocrinology, we help patients use both measurements together to create more personalized, effective diabetes management plans.
What Is A1C?
Hemoglobin A1C (HbA1C) is a blood test that measures the percentage of hemoglobin proteins in your red blood cells that have glucose attached to them. Since red blood cells live for approximately 120 days, A1C reflects your average blood sugar over the past two to three months.
For many adults with diabetes, the American Diabetes Association recommends an A1C target of less than 7%, although individualized goals may vary depending on age, health conditions, and risk factors.
Benefits of A1C
A1C remains an essential part of diabetes care because it:
- Measures long-term glucose control
- Can be measured irrespective of fasting status and time of day
- Helps diagnose diabetes and prediabetes
- Predicts the risk of long-term complications
- Is widely available and standardized
- Requires only periodic testing every 3 months
While A1C is extremely useful, it does have important limitations.
The Problem with A1C Alone
An average does not tell the whole story.
Imagine two people both have an A1C of 7%.
One person’s glucose stays relatively stable between 90 and 150 mg/dL throughout the day.
The other person’s glucose swings dramatically between 50 mg/dL and 250 mg/dL. Their highs and lows average out to the same A1C, even though their daily experience and health risks are very different.
A1C cannot show:
- Daily glucose fluctuations
- Episodes of hypoglycemia (low blood sugar)
- Episodes of hyperglycemia (high blood sugar)
- How meals, exercise, medications, stress, or sleep affect glucose levels
- Whether blood sugars remain stable throughout the day
This is where Continuous Glucose Monitoring provides tremendous value.
What Is Time in Range (TIR)?
Time in Range measures the percentage of time your glucose levels stay within a healthy target range, typically:
70 to 180 mg/dL for most adults with diabetes.
Unlike an A1C test every few months, a CGM records glucose readings every few minutes, generating hundreds of measurements every day.
Instead of simply calculating an average, Time in Range shows:
- How often your glucose is in the target range
- How often it is too high
- How often it is too low
- Daily patterns and trends
- Overnight glucose behavior
This information allows patients and providers to make much more precise treatment decisions.
Why Time in Range Matters
Research has shown that increasing Time in Range is associated with a lower risk of diabetes complications.
As a general goal:
- 70% Time in Range equals about 17 hours per day within the target glucose range.
- Every 5% increase in Time in Range represents approximately one additional hour each day spent in healthy glucose levels.
That extra hour each day can significantly improve overall glucose control over time.
A1C vs. Time in Range
| A1C | Time in Range (TIR) |
| Reflects average glucose over 2 to 3 months | Reflects glucose every day, all day |
| Requires a blood test | Measured continuously with CGM |
| Shows overall average | Shows daily highs, lows, and variability |
| Cannot identify glucose swings | Clearly identifies glucose patterns |
| Does not measure hypoglycemia | Tracks low glucose episodes |
| Helpful for long-term monitoring | Helpful for daily treatment adjustments |
Rather than replacing A1C, Time in Range complements it by providing a much richer understanding of diabetes management.
Why Continuous Glucose Monitoring Is So Valuable
CGM devices have transformed diabetes care by offering real-time glucose information without the need for frequent fingerstick testing.
Patients can immediately see how:
- Different meals affect glucose
- Physical activity changes blood sugar
- Illness or stress influences glucose
- Medications are working
- Sleep affects overnight glucose levels
This immediate feedback helps many patients make healthier decisions throughout the day.
Who Benefits from Tracking Time in Range?
Time in Range can benefit nearly anyone living with diabetes, including:
- People with Type 1 diabetes
- People with Type 2 diabetes
- Individuals using insulin therapy
- Patients experiencing frequent highs or lows
- Women with diabetes during pregnancy
- Individuals wanting tighter glucose control
Even patients with “good” A1C results may discover opportunities to improve glucose stability using CGM data.
The Importance of Personalized Diabetes Care
No two people experience diabetes the same way.
Factors such as age, lifestyle, medications, other medical conditions, and treatment goals all influence what healthy glucose management looks like.
At Sol Endocrinology, we use CGM technology alongside traditional laboratory testing to better understand each patient’s unique glucose patterns. This comprehensive approach allows us to adjust medications, nutrition strategies, and lifestyle recommendations based on real-world glucose data rather than averages alone.
The Bottom Line
A1C remains an important measure of long-term diabetes management, but it tells only part of the story.
Time in Range offers a more complete picture by showing how glucose behaves throughout the day, helping patients and providers identify patterns that A1C alone cannot reveal.
Together, these two measurements provide the most accurate assessment of diabetes control and help guide personalized treatment decisions that can improve both daily quality of life and long-term health outcomes.
Partner with Sol Endocrinology for Advanced Diabetes Care
If you’re managing diabetes or wondering whether Continuous Glucose Monitoring is right for you, the specialists at Sol Endocrinology can help. We combine the latest diabetes technology with individualized care to help you better understand your glucose patterns, improve Time in Range, and reduce your risk of complications.
Contact Sol Endocrinology today to schedule an appointment and learn how personalized diabetes management can help you achieve healthier, more consistent glucose control.