Time in Range (TiR) is a relatively new tool in diabetes care and works best when used with a continuous glucose monitor. It reflects the amount of time, usually over a 10-14-day period, that your blood glucose levels stay between a set target.
This measurement more accurately accounts for the highs and lows that a person with diabetes can experience each day.
How does it differ from an A1c?
Diatribe noted that Time-in-Range captures variation. It reflects the highs, lows, and in-range values that characterize life with diabetes. A1C, however, is a measure of average blood glucose over a two-to-three-month period. It cannot capture time spent in various blood glucose ranges.
Is Time in Range important?
TiR provides a greater focus on more stable blood glucose levels. When your glucose swings high and low throughout the day, it may cause more damage to the body than more stable readings. Maintaining a more consistent blood glucose level may be better for your overall health and wellbeing.
Why is Time in Range important?
According to one article, glycosylated hemoglobin or A1c is not a faithful measurement of “average” blood sugar control.” In some cases, variations in patient hemoglobin status because of anemia, polycythemia, chronic kidney disease, and genetic hemoglobinopathies may render A1c unreliable. TiR however provides an “immediately visible, understandable, and malleable value in patients’ day-to-day efforts at achieving good glucose control.”
How does Time in Range effect your A1c?
A 2019 article in Diabetes Technology Therapies found that there is a good correlation between A1c and Time in Range. This may permit the transition to the percentage of time in range as a preferred metric in determining the outcome of clinical studies, predicting the risk of complications, and assessing a person’s actual glycemic control.
Researchers have noted that even as much as one more hour per day of time in range can translate into improved health outcomes. Currently, the average person with diabetes will spend 50-60% of their time within target range.
Who should monitor Time in Range?
Time in Range will offer the most benefit to improved glycemic control for people with type 1 or type 2 diabetes who use insulin and wear a continuous glucose monitor.
How often should you be in range?
Goals for Time in Range can vary between patients. It will depend upon things like carbohydrate intake, type of diabetes, age, overall health, and risk of hypoglycemia.
The International Consensus Panel on Time in Range has recommended that most patients with type 1 and type 2 diabetes should strive for a Time in Range of 70% or greater. Ideally, patients should also attempt to be low no more than 4% of the time and high as little as possible.
The Consensus Panel has gone on to suggest that the optimal blood glucose range should be between 3.8mmol (70mg/dL) and 10mmol (180mg/dL). These numbers are primarily for research purposes, however. Individuals should still use a range set by their diabetes team.
By using a continuous glucose monitor and the Time in Range data, it is easier to note things like undetected lows and prolonged highs. They can also make it easier to identify patterns caused by things like increased activity on weekends, or the impact of shift changes, menstruation, or sick days on readings. This allows clinicians to guide patients more precisely with diabetes in treatment alternatives.
How do experts feel about Time in Range as a measurement of diabetes health?
A December 2020 article in the Diabetes Journal stated that the A1c does have its limitations but it still is a relevant and valuable tool in assessing overall blood glucose control and the risk of complications. When A1c is used “in combination with continuous glucose monitoring (CGM), a more accurate depiction of both acute and chronic glycemic control can be ascertained.”
Time in Range shows glucose control over a period of hours or days while A1c looks at averages over 8-12 weeks. Time in Range is not yet a fully recognized standard of measurement in diabetes care, but its value cannot be discounted.
Early studies already suggest that TIR can be a good predictor of long-term diabetes complications. The extent of the correlation between Time in Range and A1c is not yet fully apparent. A retrospective analysis of 18 articles found that for approximately every 10% change in time in range, there was an .8% change in A1c but more data is still required to confirm this.
In a time of COVID-19, when access to blood testing has been restricted, the value of Time in Range has become a welcome tool for clinicians looking to help their patients with diabetes.