Time in Range vs A1C difference in diabetes

What is the difference between Time in Range and A1C, and why do they matter?

Your diabetes management is not tied to a single number or score, but rather it’s the combination of a handful of numbers. Let’s take a closer look at two of the most common measures that many physicians use to assess your overall glucose management and treatment recommendations: A1C and TIR (Time in Range).
What is A1C?
The most common measure of diabetes health is A1C. A1C is your average blood glucose measured over a span of two to three months. This is measured by a blood test, and the higher the percentage, the higher the blood sugar levels. You can learn a little more about this test here.
So, what’s considered a standard result? Standard is considered any percentage below 5.7%. Prediabetes is indicated between 5.7% to 6.4%. For most people who have diabetes, the goal is to measure less than 7%, which has been shown in research to be associated with reduced risk of long-term complications1.
Because A1C comes from calculating an average, it can hide large swings in glucose that often happen throughout the day. This means you won’t know how much time is actually spent in low or high ranges. For example, one person may have an A1C of 7% with small glucose fluctuations between 100 and 200 mg/dL, while another may have the same A1C of 7% with large, and potentially dangerous, fluctuations between 50 and 250 mg/dL. These two patterns may result in the same A1C, but with very different energy levels, moods, and overall qualities of life for the people experiencing them. So, yes, your A1C is important to know, but it’s certainly not the whole picture.

The many faces of a 7% A1C

And an average blood glucose of 154 mg/dl
A 7% A1C corresponds to an average glucose of about 150 mg/dL
Looking for ways to lower your A1C? Find some useful tips that go beyond diet here.
What is TIR?
Time in Range (TIR) is an alternative approach to measuring diabetes health that has been made possible with the introduction of Continuous Glucose Monitoring (CGM). With measurements throughout the day, TIR is the calculation of the percentage of time a person’s glucose spends within a recommended or healthy range (most commonly this is between 70 and 180 mg/dL). The goal for most people with diabetes is to spend at least 70% of time in this range.
Where A1C is measured over the span of two to three months, TIR is calculated much more often—sometimes even daily.
So, what does TIR tell us about our health? Since it’s measured so often, we can learn more about daily factors that affect our diabetes management such as food, physical activity, illness, etc. Also, knowing how much time someone spends below 70 mg/dL and above 180 mg/dL helps explain how someone can have an A1C that appears at goal while simultaneously feeling bad throughout the day because of glucose swings. Alternatively, it provides important insight into how someone can make health behavior changes that improve their diabetes management and symptoms throughout the day but not see a change in their A1C.
Dexcom G7 CGM shows you Time in Range

Always know your TIR with Dexcom G7

One easy way to know your TIR is with Dexcom G7, where each user’s TIR is shown in real time on the home screen. Users will be able to see how much time they spend below range, within range, and above range. This helps them and their providers have more complete information to make better decisions for their health.
You can learn even more about TIR and how it can be used to control your diabetes by going here.
Together, A1C and TIR are important indicators for your diabetes management. Knowledge is power, and TIR helps us go beyond A1C with information we can use today to better manage diabetes, and our health.

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A1C vs. TIR

Time in Range vs A1C in diabetes: What's the difference
1 American Diabetes Association. Standards of Care in Diabetes. Diabetes Care. 2023;46(Supp 1):S1-S291.
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