TIR vs A1c: What’s the Difference?
Discovered in 1968, your A1c result is still valuable, but it can overlook some critical aspects of your blood sugar levels, your safety, and your overall wellbeing as a person with diabetes.
“I place immense value on time in-range because it relates directly to a person’s quality of life,” says Gary Scheiner, CDCES, MS, author of Think Like a Pancreas, and founder of Integrated Diabetes Services.
While an A1c measurement gives you a general idea of your eAG (estimated average glucose level), it won’t tell you if you’re experiencing several severe low blood sugars every day or bouncing from high to low on a regular basis. It simply provides an insight into the middle of that range. Frequent low blood sugars could also result in an artificially lower A1c result.
A1c levels are also considered a flawed measurement compared to TIR because your A1c measures the glucose attached to the red blood cells in your body, but it’s only measuring a small percentage of those red blood cells. Additionally, the newer the red blood cell is, the less attached glucose there will be, and the rate at which a person creates new red blood cells can vary wildly from person-to-person, and during other variables like pregnancy or if you just donated blood. In other words: it’s simply not a very accurate assessment of blood sugar health.
In TIR, the only variable is the general accuracy of your CGM and how often you’re wearing it. Otherwise, it can paint a very clear picture of where your blood sugars are on a day-to-day basis.
Editor’s Note: Learn more about the debate over using A1C vs TIR from ADA 2020 Pediatric Diabetes Care.