Continuous glucose monitors, or CGMs
Continuous glucose monitors, or CGMs, have changed the way people understand and manage blood sugar. Instead of checking glucose with occasional fingersticks, a CGM shows what your levels are doing all day and all night. One of the most important numbers that comes from this constant stream of data is something called Time-in-Range, often shortened to TIR. Even though it sounds technical, it is actually one of the simplest and most meaningful ways to understand overall glucose health.
Time-in-Range refers to the percentage of time glucose levels stay within a healthy target zone. For most adults with diabetes, that target is 70 to 180 mg/dL. This range comes from clinical guidelines supported by the American Diabetes Association and other expert groups. The general goal is to keep at least 70 percent of daily readings inside that zone. In practical terms, that is about 17 hours out of every 24-hour period. The remaining time should ideally include as little time as possible below 70 mg/dL or above 180 mg/dL.
What makes TIR so valuable is that it shows the full picture, not just scattered moments. Traditional markers like A1C give an average, but an average cannot reveal how often glucose is spiking high or dropping low. A person could have an A1C that looks fine on paper while still experiencing large swings throughout the day. CGM exposes those patterns clearly. It helps people identify whether their glucose tends to rise after certain meals, fall overnight, climb with stress, or react to changes in exercise. Seeing these patterns in real time makes it much easier to make adjustments that actually work.
TIR is also strongly connected to long-term outcomes. Research published in Diabetes Care shows that spending more time in range is linked with a lower risk of complications such as nerve problems, kidney disease, and vision loss. The relationship is straightforward. When glucose stays in a safe range more often, the body experiences less ongoing strain. Even small improvements matter. Just a 5 percent increase in TIR, which equals a little over one extra hour per day, can make a meaningful difference over time.
The strength of CGM is that it gives people the feedback needed to make those changes. Instead of reacting to unexpected highs or lows, CGM helps people understand the cause. You can see what happens after breakfast, during a walk, during sleep, or after a stressful day. This kind of insight is difficult to achieve with occasional fingerstick tests. CGM turns glucose management into something much more intuitive by connecting everyday actions with what the glucose trace actually does.
Time-in-Range is also a flexible target. While the 70 percent goal is a widely used standard, it is not the same for everyone. Older adults, people at high risk for low blood sugar, and pregnant individuals may have different recommended ranges. This means TIR can be personalized to match someone’s health status and lifestyle. What matters most is the direction of improvement and the stability of daily glucose patterns, not perfection.
The clarity that TIR provides often brings a sense of relief to people using CGM for the first time. Instead of guessing, you can see how your body responds to choices throughout the day. If morning readings frequently rise above 180 mg/dL, that becomes something you can work on. If evenings are more stable, that becomes something you can maintain. Over time, these small insights help create better routines, fewer surprises, and smoother daily glucose levels.
For people considering a CGM, Time-in-Range is one of the most powerful reasons to make the switch. CGM does more than provide numbers. It helps people understand their bodies, adjust habits with confidence, and work with healthcare professionals to fine-tune their treatment plans. The science behind TIR continues to grow, and experts around the world now view it as a key indicator of glucose stability and long-term health.
In the bigger picture, CGM and Time-in-Range offer tools that make life with diabetes more predictable and more manageable. When glucose levels stay in range more often, people often report better energy, clearer thinking, improved sleep, and fewer interruptions to daily activities. That is the real value of this technology. It gives users insight, control, and a path toward steadier health each day.
References:
https://pmc.ncbi.nlm.nih.gov/articles/PMC11965008/
https://diabetes.org/about-diabetes/devices-technology/cgm-time-in-range
