As more and more people are introduced to the wonderful world of real-time continuous glucose monitoring (RT-CGM), there is growing attention being paid to “percent time-in-range” (or %TIR), rather than just A1c.
And for a pretty good reason! Percent time-in-range refers to the amount of time you spend each day (or each week, or each month) in the reasonably safe range of 70 – 180 mg/dL. Not the perfect glucose range, just the reasonably safe range! The belief is that %TIR may be a more useful predictor than A1c of how well you are doing with your diabetes and what your risk might be for serious problems down the road. And if you’re wearing an RT-CGM, you can find out rather accurately about your %TIR and how it might be changing any time you want. Want to know how you’re doing right now? No need to just wait three months or more to hear about your latest A1c result.
So, by increasing your %TIR to at least 70% (the goal as set by a recent international body), you are likely to be enhancing your long-term health. But might it also be good for your quality of life? Does your %TIR affect how you feel?
This may seem like an obvious question, since many of you have already noticed that you may not feel so great when your glucose levels are too low or too high. But there is little science that has documented this. Until now. Just a few months ago, my colleague Dr. Addie Fortmann and I published a study where we surveyed 219 adults with type 1 diabetes. All of them were currently wearing a Dexcom G6 RT-CGM and they were kind enough to share their CGM data with us. In addition, each evening for two weeks, they completed a questionnaire where they were asked to reflect on how they had been feeling during that day. The results were exactly what you might have expected: on days where %TIR was greater, people reported feeling more cheerful, more full of energy, calmer and more relaxed. On those same days, they also reported feeling less exhausted than usual, less frustrated, irritable and anxious. In other words, better %TIR over the course of the day—when there are fewer wacky highs and fewer annoying lows– seems to contribute to better mood.
But here are two things we don’t yet know:
First, all of the people in our study could see their own glucose numbers. And so, reflecting back on his day this evening, does the individual feel better because he sees that his glucose values have been “doing better” today (in other words, greater %TIR)? Or perhaps he is feeling better today as a result of some direct physiological change, whereby greater %TIR leads to less fatigue and greater mental clarity, which then causes him to feel better? Or maybe it is both? Until we do further studies, we can’t know for sure.
Second, we don’t know if better %TIR might also lead to a better mood for people with T2D, or perhaps even for people with prediabetes. Stay tuned for future research investigations!
The bottom line is this: we know that %TIR of at least 70% is likely to be important for your long-term health, and we can now say with some confidence that helping you to achieve better %TIR is better for your mental health as well. So if you’ve been struggling with your diabetes care and you’ve also been down in the dumps, please know that by working with your RT-CGM and your healthcare team to achieve greater success with your glucose control, you’ll probably be also doing a good thing for your spirits.
Given your own experience, what do YOU think? Please share your thoughts in the comments below.