For decades, hemoglobin A1C (A1C) has been the gold standard for assessing diabetes management. Estimating average blood glucose over the past two to three months, it has long guided treatment decisions for people with diabetes.
Yet not all glucose measurements tell the same story.
A1C doesn’t capture day-to-day variability. As a result, even a “normal” A1C value can mask significant glucose swings — changes that can impact not just health, but quality of life.
That’s why more people with diabetes, clinicians, and researchers are turning to time in range (TIR) — a metric made possible by continuous glucose monitoring (CGM) that offers a fuller picture of daily glucose management.
As the graphic illustrates, the same A1C can tell three very different stories.
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The image above is approved for use by DiaTribe.
Unlike A1C, TIR tracks the percentage of time glucose levels are within a set target range — providing actionable information to guide everyday diabetes decisions.
Studies consistently show that spending more time in range is associated with a lower risk of diabetes-related complications. Simply put, the more time your glucose levels stay in a healthy range, the better. This makes TIR a valuable measure for both providers and people living with diabetes.
Few people have witnessed this evolution more closely than Julie Heverly, Vice President of the Time in Range Coalition and Patient Advocacy at The diaTribe Foundation. Heverly recently spoke with T1D Exchange about why TIR is changing the conversation around trusted diabetes measurements, how it empowers people living with diabetes, and why she believes it’s time to look beyond averages like A1C.
A personal experience that changed everything
“One day, my endocrinologist called and left a message saying: ‘Your A1C is perfect. Don’t change a thing,” said Heverly, who didn’t answer her phone, because at that exact moment, she was having a 45-minute hypoglycemic event.
It was a stark reminder that A1C wasn’t telling the whole story. By using time in range, she and her healthcare team made dosing changes to decrease the number of lows she was having.
Today, her endocrinologist still checks her A1C — mostly to satisfy insurance requirements — but it’s no longer the focus of their conversations. Instead, they discuss time in range and AGP report values, both produced from her CGM data.
“This information has proven significantly more helpful in making sure what’s actually happening in my life is being addressed at my medical appointments,” she said. “Rather than relying on the 3-month average, we can impact what my days look like and how productive I can be.”
What is the Time in Range Coalition?
The Time in Range Coalition is a collaboration of more than 30 organizations, including diabetes nonprofits, healthcare professionals, industry partners, and patient advocacy organizations, working to advance wider use of CGM metrics in both research and clinical care.
To Heverly, improving diabetes care means more than helping people understand the value of their CGM data and using it to empower their daily choices. It also means changing how people think about the relationship between data and diabetes outcomes — and ensuring everyone has access to the tools they need to support better health.
“Our goal is to raise awareness and adoption of CGM metrics for people living with diabetes and healthcare providers,” said Heverly. “But, we also know that if people don't have access, and it's not being recognized by regulatory bodies — they won't be able to benefit from these tools.”
To move that work forward, the Coalition focuses on three key areas: education and awareness, policy and advocacy, and fostering collaboration across diabetes organizations.
That collaborative approach is what excites Heverly most.
“All of our partners bring resources, knowledge, and expertise to the table,” she said. “It’s inspiring to see so many organizations working together to support an initiative that can improve outcomes and empower people with diabetes.”
Bringing those perspectives together is what sets the Coalition apart. When technology companies, nonprofit organizations, clinicians, and patient advocates rally behind the same goal, she believes it sends a powerful message.
“When you hear everyone saying, ‘This is really important work,’ it reinforces its importance for the entire community.”
Ultimately, Heverly wants people to know that time in range is about more than just another diabetes metric.
“Time in range is the beginning of personalized care. It’s a data point you can use not just once a quarter, but one that lets you see in real time how living affects glucose. It can empower people with fluid information and help them thrive with diabetes.”
WHAT IS TIR?
Time in range measures the percentage of time your glucose stays within your target range.
While TIR goals should be individualized — taking into account other health conditions, age, hypoglycemia risk, and personal circumstances. General recommendations include:
- Target range: 70-180 mg/dL
- Goal for many adults: 70% or more time spent within this range about 17 hours of your day), and is roughly equivalent to an A1C of 7.0%.
- Real-time insights: TIR uses CGM data to provide daily, actionable information
- Complements A1C: Unlike A1C, TIR shows daily glucose fluctuations and patterns
WHAT IS TIME ABOVE RANGE (HYPERGLYCEMIA)?
Time above range measures the percentage of time your glucose is above your target range.
- Level 1: 181-250 mg/dL — Goal: Less than 25% of your day
- Level 2: Above 250 mg/dL — Goal: Less than 5% of your day
WHAT IS TIME BELOW RANGE (HYPOGLYCEMIA)? Time below range measures the percentage of time your glucose is below your target range.
- Level 1: 54-70 mg/dL — Goal: Less than 4% of your day
- Level 2: Below 54 mg/dL — Goal: Less than 1% of your day
How does CGM technology change lives?
The value of time in range extends beyond numbers. It empowers people with the knowledge and confidence to make informed decisions about T1D each and every day.
For many people, time in range isn't just about better numbers. It’s about sleeping through the night with fewer lows, feeling more confident exercising, and spending less time worrying about diabetes.
To help make that possible, the Time in Range Coalition has created educational toolkits for healthcare professionals and people with T1D. These resources include videos, conversation guides, CGM education, and practical tools — all created by people with diabetes and healthcare professionals. They help people understand their data and have more meaningful conversations with their care team about diabetes-related goals.
While the Coalition is best known for championing time in range, its work continues to expand. Recent efforts include an international consensus on how CGM can be standardized in clinical trials and recent international consensus guidance on the use of diabetes technology during pregnancy. Together, these efforts provide practical, evidence-based guidance for both providers and people living with diabetes.
In Summary
Technology hasn’t solved every challenge of living with diabetes, Heverly acknowledged. But she believes it has fundamentally changed what’s possible — and that the next generation may benefit even more.
“We’re going to keep working as hard as we can to make that happen,” she said.
For Heverly, that commitment is deeply personal. Her experience illustrates why time in range matters. By providing a more complete picture of daily glucose patterns, it has helped her to make more informed decisions, reduce hypoglycemia, and thrive with type 1 diabetes.
