Time in Tight Range: What the New CGM Metric Means for People With Type 1 Diabetes

Continuous glucose monitors have changed how we measure blood sugar control. For years, the standard goal has been time in range (TIR): the percentage of time your glucose stays between 70 and 180 mg/dL. Now researchers are looking at an even tighter target called time in tight range, or TITR, which sets the upper limit at 140 mg/dL instead of 180.

TITR was formally proposed in 2023 as a way to assess glucose control more precisely. The idea is that staying closer to normal glucose levels might offer extra protection against complications. But whether this stricter target actually delivers better outcomes—and for whom—is still being investigated.

Studies so far have found that TITR correlates strongly with both HbA1c (your three-month average) and traditional time in range. That means if your TITR is good, your other glucose metrics tend to be good too.

Some cohort studies suggest that people spending less time in tight range have higher risks of death from all causes and heart-related events. Meanwhile, higher TITR has been associated with lower rates of diabetic retinopathy, an eye complication. These patterns are encouraging, but they come from observational studies—not the kind of research that proves cause and effect.

TITR has even shown associations with better outcomes in people with Type 1 diabetes who developed severe COVID-19 pneumonia, though this finding is preliminary.

Researchers emphasize that TITR shouldn't be interpreted in isolation. How much your blood sugar bounces around (glycemic variability) can affect your TITR reading in different ways depending on your average glucose level, which complicates the picture.

There's also a practical concern for people using multiple daily injections: pursuing higher TITR without careful oversight can lead to more time spent below range—in other words, more low blood sugar events. This is a real safety trade-off that needs attention.

The bottom line from researchers is that TITR might be useful for tracking progress when your glucose is already close to target, but it's too early to say it should replace established CGM metrics for everyone.

Before TITR becomes a standard goal in diabetes care, scientists need to conduct prospective studies—research that follows people over time to see whether higher TITR actually prevents complications and improves long-term health.

They also need to figure out what the optimal TITR target should be for different groups of people with Type 1 diabetes, and whether the benefits hold across diverse populations and insulin regimens.

For now, if your healthcare team mentions TITR, it's worth asking how it fits with your existing glucose targets and whether pursuing it makes sense for your individual situation.

Source: Diabetology international. Evidence type: PubMed indexed literature. Type1Cure is an information and intelligence hub, not a medical advice service. This article summarizes published research and does not provide diagnosis, treatment, or personal medical guidance. Always talk to your own care team before changing anything about your Type 1 diabetes management.