Time in Tight Range: A New Diabetes Goal?
You have probably heard of time in range (TIR), but time in tight range (TITR) has slowly become popular among some diabetes experts. Whereas guidelines generally define time in range as a range of between 70 to 180 mg/dl, time in tight range is defined as between 70 to 140 mg/dl.
Just like standard TIR, TITR should be measured using a continuous glucose monitor (CGM).
“Time in tight range describes the time an individual spends in normoglycemia [normal levels of blood glucose],” said Dr. Thomas Danne, director of the Department of General Pediatrics Endocrinology/Diabetology & Clinical Research at Children's Hospital Auf der Bult in Hanover, Germany. He spoke as part of a panel on the new metric at the Advanced Technologies and Treatments for Diabetes (ATTD) conference in Berlin, Germany.
The metric essentially lowers the upper threshold for higher glucose levels. “Elevated glucose is harmful, which is why we need a tight range,” said Dr. Tadej Battelino of the University of Ljubljana at the session.
Spending 18% or greater time above 140 mg/dL predicts the progression of diabetes in children with autoantibodies (who are at higher risk for type 1 diabetes), explained Danne, citing a 2019 study. Additionally, a Swedish study concluded that having type 1 diabetes and an A1C of just below 7% which is thought to translate to a time in range of about 70% still significantly increases one’s risk for cardiovascular disease.
It is generally recommended to minimize time above 180 mg/dL as much as possible, which is why that is the upper limit for the standard time in range, but it is possible that some individuals may see greater benefits with 140 mg/dl. According to Danne, time in tight range could potentially lead to a longer life expectancy as it reduces the risk of complications.
Time in tight range can be used for timely therapy intensification and optimization, explained Battelino. “The higher the A1C, the higher the risk of dementia for people with type 2 diabetes,” which is why he proposes a focus on time in tight range.
Because of the possible benefits that early and aggressive treatment can bring, some experts have proposed a focus on time in tight range for preschoolers with diabetes.
Another panelist, Peter Adolfsson explained that CGM is the recommended tool for glucose monitoring for this population and when using a CGM, a reasonable treatment target is 50% time in tight range (3.9-7.8 mmol/l, or 70-140 mg/dl).
Time in tight range is a more challenging goal to achieve than time in range, but diabetes technology like CGM, and automated insulin delivery (AID) can help make it possible.
“There is a fast and ongoing evolution of technology that enables a greater proportion of individuals to reach high goals,” said Adolfsson. “High goals can be achieved without increased acute complications.”