Time in Range: How CGM Metrics Transform Diabetes Management

For people with diabetes, knowing your average blood sugar isn't enough. What matters is how often your glucose stays in the safe zone. Time in Range is a metric that tracks the percentage of time your blood sugar stays between 70 and 180 mg/dL (3.9-10.0 mmol/L), measured by a continuous glucose monitoring (CGM) device. It's like a real-time snapshot of your glucose control, not just a three-month average.

CGM devices measure your glucose every few minutes. Unlike traditional finger-prick tests, these sensors provide up to 20,000 data points in two weeks. This detailed data helps spot patterns you'd miss with HbA1c alone.

Why Time in Range Beats HbA1c

HbA1c gives a three-month average of your blood sugar. But it can't tell you when your glucose spikes after meals or drops overnight. Two people with the same HbA1c level might have very different daily experiences. One could have stable glucose all day, while the other has dangerous lows and highs. That's why Time in Range is becoming a game-changer.

A 2023 Cleveland Clinic study found that patients with identical HbA1c levels had drastically different Time in Range values. Those with lower Time in Range had higher risks of complications like nerve damage, even when their HbA1c seemed "good." This shows why daily glucose patterns matter more than just an average number.

Real-World Impact

A patient named Sarah, diagnosed with type 2 diabetes, noticed her HbA1c was 7.2%-within the target range. But her Time in Range data showed she spent only 55% of the day in range. She discovered unexpected spikes after eating what she thought were healthy snacks like granola bars. Switching to protein-rich options and adjusting her medication timing increased her Time in Range to 78% in just three weeks. "I finally understood why I felt shaky sometimes," Sarah said. "Time in Range gave me the details my HbA1c couldn't."

Steps to Improve Time in Range

Here's how you can use Time in Range data to improve your diabetes management:

• Track meals and activity: Note what you eat and how you feel after. If your Time in Range drops after eating rice, try swapping it for quinoa or barley.
• Adjust medication timing: Some diabetes meds work better when taken before meals. Talk to your doctor about timing adjustments based on your CGM data.
• Exercise timing: A short walk after dinner can lower blood sugar spikes. Check your Time in Range data to see what works best for you.
• Avoid late-night snacks: Late eating often leads to morning highs. Aim for your last meal 2-3 hours before bed.
• Check patterns weekly: Look for trends in your Time in Range data. If you notice consistent lows overnight, adjust your nighttime insulin dose (with your doctor's guidance).

Overcoming Challenges

CGM devices can be expensive. Insurance coverage varies widely. But the 2025 ADA Standards of Care now recommend CGM for all adults with type 2 diabetes using glucose-lowering medications-not just insulin users. Medicare has expanded coverage, making CGM accessible for many more people. Still, some face hurdles. If your insurance denies coverage, talk to your healthcare provider about submitting a letter of medical necessity. Organizations like the American Diabetes Association also offer assistance programs.

Major Dexcom, Abbott, and Medtronic CGM brands continue to improve sensor accuracy and reduce costs. Newer models like Dexcom G7 and Abbott FreeStyle Libre 3 are smaller, more accurate, and require less frequent calibration.

The Future of Time in Range

Artificial intelligence is starting to predict glucose trends. Some CGM systems now suggest insulin doses based on Time in Range data. Researchers are also studying "time in tight range" (70-140 mg/dL), which may offer even better protection against complications. As technology improves, Time in Range will likely become a standard part of diabetes care alongside HbA1c.