Time in Range: Why is it Important?

June 8, 2021
Jenna Feeley
University of Maryland College Park '21
Jenna has been living with T1D since 2010. Passionate about community building, she started the University of Maryland chapter in 2019. Through her path navigating T1D, as well as talking with others about their journeys, Jenna has discovered her love of psychology and medicine. She is currently pursuing a career in healthcare. Jenna is also a volunteer for Camp Possibilities and the(sugar)science, two organizations that aim to enhance the lives of those living with T1D. In her free time Jenna enjoys podcasting, exercising, and talking to friends and family.

Hi everyone! I’m Jenna and I’m a 2021 NextGen Fellow with The Diabetes Link. I’ve been living with T1D for about 11 years and have been using a CGM for 6 of those years. Although I rely heavily on my CGM for daily management, I didn’t fully understand how I could use time in range to gain a better understanding of my daily blood sugar trends.

Therefore, when the opportunity to interview Gary Scheiner, MS CDCES presented itself I thought it would be a great way to learn more about this topic. Gary is the founder and clinical director of Integrated Diabetes Services, a clinical practice that helps insulin dependent diabetics learn the tools necessary to live healthier and happier lives. Gary provided some great practical tips and insight into time in range and how it can be used in daily management.

Jenna: Can you talk about how you define “time in range” and why it’s so important for young adults to be familiar with this term?

Gary: Time in range tells us about how much time we spend in our unique healthy range. Having a continuous glucose monitor (CGM) is the most efficient way of measuring this. Time in range is an important measure because it tells us about the quality of our management by indicating the amount of time our blood sugars are where we feel the best. In contrast, A1c indicates our average blood sugar over the past three months. Because this measures our average blood sugar instead of the time spent within our unique healthy range, A1c gives us much less specific information about the overall quality of our management.

“Time in range is an important measure because it tells us about the quality of our management by indicating the amount of time our blood sugars are where we feel the best. ”

Jenna: How do we determine our target ranges?

Gary: In general, 70mg/dl is an often recommended goal for the lower limit while 150-200mg/dl is a good goal for the upper limit. The upper limit or your “high” target will vary with both lifestyle and goals. For example, someone who has seen a pattern of higher blood sugars and wants to gradually bring their numbers down may start by setting their upper limit at 200 mg/dl. In contrast, someone who wants to manage aggressively (e.g. preparing for pregnancy) would likely set their upper limit closer to 150 mg/dl. The “Time in Range” definition is considered the percentage of time of a course of several days up to several months that your data shows you are spending within those high and low targets. The targets can be changed and altered for different times of day as you continue to change your day to day routines and individual plans.

One interesting point to note is that even at 180mg/dl the body starts to show symptoms of high blood sugars such as spilling glucose into the urine, increased thirst and urination, dehydration, and energy loss. Therefore, setting the upper limit at 180 will help to prevent these symptoms from interfering with everyday life. 70 is generally a good goal for the lower limit; one exception to this is if someone has hypoglycemia unawareness. It may be healthier for them to set their lower limit at 80.

“One interesting point to note is that even at 180mg/dl the body starts to show symptoms of high blood sugars.”

Jenna: What is a good target for time in range?

Gary: 70-75% time in range is a good target. Less than 3% of the day should be spent hypo. This is important because each 1% is ~15 minutes, and more than 45 minutes per day at a hypo level is not healthy.

Jena: What advice would you give to young adults who are really trying to increase their time in range?

Gary: Set alerts at appropriate numbers. This should be 10 points above the lower limit and 10 points below the upper limit. When an alarm goes off, make sure to act right away – “don’t think, just act.”

Jenna: How should patients and healthcare providers “use” A1c and time in range?

Gary: A1c and time in range can be used together. Both are shown to be correlated to complication risk. Importantly, time in range is correlated with both hypoglycemia and hyperglycemia risk and quality life measures. The time in range data can be used to determine the numbers that contribute to the A1c value.

After talking to Gary about time in range, I logged into my Dexcom Clarity account and adjusted my target ranges. I had no idea that time in range targets are separate from where I set my high and low alerts! Now that I understand these different tools that Dexcom provides, I’m able to tailor my high and low alerts to my desired target range. I hope this article helps you do the same!

Thank you to Dexcom, our Silver Level Sponsor of We Speak Diabetes: Time in Range!

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