What is Time in Range — and Why It Matters More Than A1c
For decades, A1c was the only number that mattered in diabetes management. But over the last few years, a new metric has taken center stage — one that gives you a far more complete picture of how your blood sugar is actually behaving day to day.
That metric is Time in Range (TIR). And if you're managing diabetes with a CGM or even just checking your glucose regularly, it's the number you should be watching most closely.
What is Time in Range?
Time in Range is the percentage of time your blood glucose stays within a target range — typically 70–180 mg/dL for most people with Type 1 or Type 2 diabetes.
Example: If your glucose was within 70–180 mg/dL for 17 out of 24 hours, your TIR for that day would be about 70%.
The American Diabetes Association (ADA) recommends a TIR of at least 70% as a general target for people with diabetes. For older adults or those at higher risk of hypoglycemia, the target is slightly lower.
TIR Targets by Population
| Population | Target TIR | Range |
|---|---|---|
| Most adults with T1 or T2 | >70% | 70–180 mg/dL |
| Older adults / high hypoglycemia risk | >50% | 70–180 mg/dL |
| Pregnancy (T1) | >70% | 63–140 mg/dL |
Why TIR Matters More Than A1c
A1c gives you a 90-day average — but averages can be misleading. Two people can have the same A1c of 7.0% while living completely different lives. One person might have steady, stable glucose all day. The other might swing between extreme highs and lows that cancel each other out mathematically.
TIR captures what A1c misses:
- Glucose variability — how much your levels swing up and down
- Time spent low — dangerous hypoglycemia that A1c can hide
- Time spent high — the specific windows where your glucose runs elevated
- Daily patterns — which meals, times of day, or activities cause problems
How to Improve Your TIR
1. Log meals with carb counts
The single biggest driver of time out of range is post-meal glucose spikes. Logging what you eat — especially net carbs — lets you see exactly which meals push you high and for how long. Over 30 days, patterns emerge that you can act on.
2. Check glucose before every meal
Starting a meal already elevated means you'll spike higher and take longer to come back down. A pre-meal reading above 140 mg/dL is a signal to wait, go for a short walk, or adjust your dose before eating.
3. Move after meals
Even a 10-minute walk after eating can reduce your post-meal spike by 20–30 mg/dL. Exercise opens glucose transporters in your muscles that work independently of insulin — meaning it works even when insulin resistance is high.
4. Identify your worst windows
Most people have predictable windows where their glucose runs high — early morning (dawn phenomenon), after a specific meal, or late at night. Once you identify yours, you can target those windows specifically rather than trying to improve everything at once.
5. Sleep
Poor sleep raises cortisol, which directly raises fasting glucose. Even one bad night can drop your TIR by 5–10% the next day. Protecting sleep is one of the most underrated diabetes management strategies.
Track Your Time in Range with Sugar Smart
Sugar Smart shows your daily and weekly TIR, identifies your worst glucose windows, and sends you challenges that complete automatically when you hit 70%+ TIR for 3 days. Free on iPhone.
Download Free on the App StoreWhat Counts as Time Below Range?
TIR has two important companions — Time Below Range (TBR) and Time Above Range (TAR).
- Time Below Range: glucose under 70 mg/dL. The ADA recommends keeping this under 4% of the day (about 58 minutes). Under 54 mg/dL should be less than 1%.
- Time Above Range: glucose over 180 mg/dL. Aim to keep this under 25% of the day.
When working to improve TIR, always prioritize reducing time below range first. Hypoglycemia carries immediate risks that hyperglycemia typically does not.
The Bottom Line
A1c is still important — it's what your doctor uses and it reflects long-term risk. But TIR tells you the story A1c can't. It shows you what's actually happening every hour of every day, which meals spike you, which times of day you struggle, and whether the changes you're making are actually working.
If you're only tracking A1c, you're flying with half the instruments. Start tracking Time in Range and you'll have everything you need to make real improvements.