The Importance of Time in Range for Diabetes Care

Lindsay Cohen, RDN

Credit: Mama-Betes

The hemoglobin A1c test has been the gold standard for assessing diabetes management for many years. It provides a snapshot of average blood sugar control over the past three months. However, we now know that a single number can’t tell the whole story.

While an A1c of 6.5% might seem like a win, it could mask a roller coaster of blood sugar highs and lows, which is a reality many people with diabetes experience.

This is where time in range (TIR) comes in, providing a picture of what is actually happening with blood sugar levels throughout the day.

Time in Range versus A1c

TIR is the percentage of time your blood sugar levels are within a target range. While the specific range can vary based on your individual needs and your health care provider’s recommendations, the general goal is typically 70 to 180 milligrams per deciliter (mg/dL). TIR is generally measured using a continuous glucose monitor (CGM). Unlike traditional finger-stick tests, which provide a single data point, CGMs offer continuous data, allowing you to see trends and patterns.

While the A1c test remains an important tool, it has limitations. Consider two people with an A1c of 7.0%. Person A might have stable blood sugars that rarely deviate from their goal range, while Person B might experience frequent and dramatic spikes and crashes. Even though their A1c is the same, Person B is at a much higher risk for hypoglycemia and long-term complications.

The A1c test alone cannot distinguish between these two scenarios, which is why focusing on TIR provides a more complete and accurate view of everyday diabetes control.

Why Time in Range Matters

Improving TIR reduces the risk of both short- and long-term complications. The Diabetes Control and Complications Trial demonstrated that better blood sugar control reduces the risk of long-term complications. More recent research on CGM data from various studies has reinforced this, showing that each additional 5% of time spent in range can lead to significant reductions in the risk of retinopathy and nephropathy.

Beyond preventing future complications, maintaining an ideal TIR can also dramatically improve quality of life. Consistent blood sugar levels means fewer episodes of fatigue, brain fog and irritability that often come with glucose fluctuations.

Understanding the Key Metrics

When reviewing CGM data, two additional metrics beyond TIR are often used. These include time above range (TAR) and time below range (TBR).

• TIR: The percentage of time your glucose is in your target range (e.g., 70-180 mg/dL). A higher percentage is better, with a goal of over 70% generally recommended.
• TAR: The percentage of time your glucose is above your target range. This is further broken down into Level 1 (e.g., 181-250 mg/dL) and Level 2 (>250 mg/dL) highs. Your goal should be to minimize this number, especially Level 2 highs.
• TBR: The percentage of time your glucose is below your target range. This is also broken down into Level 1 (e.g., 54-69 mg/dL) and Level 2 (<54 mg/dL) lows. Hypoglycemia can be dangerous, so minimizing TBR, particularly Level 2 lows, is key. A TBR goal of less than 4% is generally recommended.

By being aware of these three metrics, you and your health care team can identify specific patterns. Are your blood sugars spiking after meals? Are they dropping overnight? This information will help you to make appropriate adjustments to your diet, medication and physical activity to help improve your TIR.

6 Strategies to Increase Your Time in Range

Below are some strategies to help increase your TIR:

1. Monitor with a CGM: A CGM provides real-time feedback on how your body responds to food, exercise, stress, medication and other factors.
2. Focus on balanced meals: Carbohydrates have the most significant impact on blood sugar, but a balanced meal includes protein, fiber and healthy fats.
3. Stay active: Regular exercise, even a short walk after a meal, can significantly improve insulin sensitivity and help lower blood sugar levels.
4. Stay hydrated: Drinking water can help flush excess glucose through the kidneys, which may also help improve blood sugar levels.
5. Manage stress and sleep: Stress hormones can raise blood sugar levels, and poor sleep can negatively impact insulin sensitivity. Prioritizing stress-management techniques and getting enough rest are important parts of diabetes management.
6. Work with your health care team: Use your CGM data to have a conversation with your doctor or diabetes educator. They can help you interpret your trends and make necessary adjustments to your routine.

Shifting the focus from A1c alone to also include TIR marks an important step forward in diabetes care. TIR offers a more complete picture of daily blood sugar patterns, empowering you to aim for greater stability and, in turn, a healthier and more balanced life.