You just got your A1C back. It’s a 6.7%. Your endocrinologist is high-fiving you, the lab report looks "green," and on paper, you’re the model patient. But here’s the reality: You feel like absolute trash. You’re exhausted, your mood is swinging like a pendulum, and you’re carrying the mental weight of a thousand "WTF" moments where your blood sugar spiked to 300 for no reason.
Time in Range (TIR) is the percentage of time your blood glucose stays within your target range, typically 70–180 mg/dL. While A1C is a three-month average, TIR tells you how you actually lived those 90 days. For most of us with T1D, a "good" A1C can hide a chaotic roller coaster of highs and lows. Improving your TIR: aiming for the clinical gold standard of 70% or more: is the real secret to feeling human again and protecting your long-term health.
We’ve been sold the A1C as the ultimate grade on our report card. But A1C is a blunt instrument. It’s an average.
Think of it like a pilot flying a plane. Pilot A stays at a steady 30,000 feet for the entire five-hour flight. Pilot B nosedives to 5,000 feet, then panics and climbs to 55,000 feet, bouncing back and forth the whole way. On average, both pilots flew at 30,000 feet. But Pilot B’s passengers are terrified, sick, and probably never flying again.
That’s what a roller-coaster blood sugar day feels like. You can have a "perfect" average because your 300 mg/dL spike was canceled out by that terrifying 45 mg/dL crash at 3 AM. Your A1C looks great, but your body is suffering from the "velocity" of those changes.
When we talk about TIR T1D metrics, we are looking at the data from your Continuous Glucose Monitor (CGM). It breaks your day down into three buckets:
The clinical consensus from the American Diabetes Association (ADA) is that we should aim to be "In Range" at least 70% of the time. That’s roughly 17 hours out of a 24-hour day.
But it’s not just about a number on a screen. Being "In Range" is a physical feeling. It’s the difference between having the energy to finish your workday and needing a three-hour nap because your blood felt like syrup all afternoon.
If you want to know what is time in range diabetes experts are obsessed with lately, it comes down to two things: how you feel today and how you’ll feel in twenty years.
Research shows that huge fluctuations in blood sugar: even if the average is okay: cause oxidative stress and inflammation. It’s the "yo-yo" effect that wears down your blood vessels.
More importantly for those of us living this every day, TIR is a better reflection of our mental load. Highs cause brain fog, irritability, and thirst. Lows cause anxiety, shakiness, and that weird "I need to eat everything in the pantry" primal hunger. When you increase your TIR, you aren't just hitting a clinical goal; you're reclaiming your personality from the highs and lows.
This is where the frustration sets in. You count the carbs. You bolus. You wait 15 minutes. And you still end up at 250 mg/dL. Why?
Because the "Carbs + Insulin = Result" equation is an oversimplification. It’s a lie we’re told at diagnosis to keep us from losing our minds. The reality is that there are dozens of "hidden variables" that shift your insulin sensitivity every single hour.
If you don't account for these, you'll spend your whole day "rage bolusing": over-correcting for a high, which leads to a low, which leads to an over-treatment, and the cycle repeats.
Most people think improving TIR means being "stricter" or having more willpower. It doesn't. Willpower is a finite resource, and T1D is a 24/7 job. You can’t "will" your pancreas back to life.
Instead, improving TIR is about pattern recognition.
If you only look at your CGM when it beeps at 200 mg/dL, you’re already behind. You’re playing defense. Improving TIR requires playing offense. Look for the trend. If you see a diagonal arrow up at 140 mg/dL, that’s the time to act: not when you hit 200.
We all have one or two things that predictably wreck our day. For some, it’s poor sleep. For others, it’s high-intensity exercise that causes a temporary spike before a drop. Once you identify your personal "hidden variables," you can adjust your basal rates or boluses proactively.
Don't try to go from 50% TIR to 90% overnight. It’s impossible and you'll burn out. Aim for a 5% improvement. That’s just 72 extra minutes a day in range. Maybe that means pre-bolusing for breakfast five minutes earlier or taking a 10-minute walk after dinner. Small shifts create massive compound results.
At Subseven, we live this. We know that the "stressing and guessing" is the hardest part of the disease. We didn't need another app to tell us our blood sugar was high: we needed a tool to tell us why.
The key to moving the needle on TIR isn't doing more math; it's understanding the context. When you start to see how your stress levels, sleep quality, and even the weather affect your insulin sensitivity, the chaos starts to look like a map. You stop blaming yourself for the spikes and start managing the patterns.
Improving your Time in Range isn't about achieving a "perfect" flat line. Perfection is a myth in T1D. It’s about building a life where diabetes takes up less space in your brain.
What is a good time in range percentage?
For most adults with Type 1 or Type 2 diabetes, the target is usually above 70%. However, your specific goals should be discussed with your doctor, as age and pregnancy can shift these targets.
Is a 100% Time in Range possible?
It's possible for a single day, but it's rarely sustainable or necessary. Chasing 100% often leads to extreme burnout. Stability and "mostly in range" is a much healthier mental goal than perfection.
Does TIR replace A1C?
Not yet. A1C is still the standard for predicting long-term complication risks in clinical settings. Think of them as partners: A1C gives the big picture, while TIR gives the daily tactical data.
How does exercise affect TIR?
It’s a double-edged sword. Aerobic exercise (like jogging) usually increases TIR by burning glucose, but anaerobic exercise (like heavy lifting) can actually cause a temporary spike in blood sugar, temporarily lowering your TIR.
Can I improve my TIR without a CGM?
It is significantly harder. Finger sticks only provide a "snapshot" in time. To truly understand TIR, you need the continuous data stream that a CGM provides to see what happens between the tests.
What is the "Standard Deviation" in TIR?
Standard deviation measures how much your glucose varies from the average. A low standard deviation means you have a "flat" line, while a high one means you’re on a roller coaster. Usually, a SD of less than 33% of your mean glucose is the goal.
About the Author:
Chris Putsch is the founder of Subseven and has lived with Type 1 Diabetes for years. He built Subseven to help others move past the "guessing" of T1D management by focusing on the hidden variables that the traditional medical model often misses. His mission is to help the T1D community find more freedom through better data insights.
Ready to take the guesswork out of your management? Download the Subseven app and start seeing the patterns behind your numbers.
