If you have Type 1 diabetes, you’ve probably been told that exercise lowers blood sugar.
Sometimes it does.
Sometimes it doesn’t.
In fact, I’ve had workouts where my blood sugar has dropped steadily, and others where it’s actually gone up. It can be frustrating when you’re doing the “right” thing but your glucose has other ideas.
Over time, I’ve learned that the type of exercise, the timing of my insulin and even the time of day can all make a difference.
Here’s what I’ve learned, along with what the evidence says.
Why Exercise Affects Blood Sugar
When you exercise, your muscles use glucose for energy. This often causes blood sugar levels to fall, especially during longer periods of moderate activity.
However, exercise also causes your body to release hormones such as adrenaline. These hormones can temporarily raise blood sugar, particularly during short, intense workouts.
That’s why there isn’t a one-size-fits-all answer.
Walking And Light Cardio
For me, walking is one of the easiest ways to help manage my blood sugar.
A 15 to 30-minute walk after a meal often helps reduce a spike, although the effect isn’t always identical.
Steady activities such as walking, cycling and swimming are more likely to lower blood sugar gradually.
Related reading:
Weight Training
Strength training can be different.
I’ve occasionally finished a gym session expecting my blood sugar to be lower, only to find it’s gone up slightly.
This can happen because high-intensity exercise triggers stress hormones, causing the liver to release stored glucose.
The rise is often temporary, but it’s another reminder that exercise doesn’t affect everyone in the same way.
Active Insulin Matters
One of the biggest things I’ve learned is to think about how much insulin is already working in my body.
Exercising soon after a meal, when rapid-acting insulin is still active, can increase the chance of going low.
On the other hand, exercising several hours later may have a completely different effect.
Time Of Day
I’ve also noticed that the same workout can produce different results depending on when I do it.
Morning exercise doesn’t always affect me the same way as an evening session.
That’s why I try to focus on patterns rather than expecting identical results every day.
Your Blood Sugar Before Exercise
Starting exercise with a blood sugar of 12 mmol/L is very different from starting at 6 mmol/L.
Checking your glucose beforehand helps you decide whether you need a snack, insulin adjustment or simply to monitor more closely.
What Helps Me
These habits have made exercise much less stressful:
- Checking my Libre before I start.
- Carrying hypo treatment every time.
- Keeping water with me.
- Looking for patterns instead of reacting to one workout.
- Accepting that not every session will have the same outcome.
Products That Help
A simple way to carry glucose tablets, keys and your phone.
Staying hydrated is important before, during and after exercise.
Easy to carry in your pocket or gym bag.
Keeps insulin, snacks and diabetes supplies together.
Frequently Asked Questions
Why does my blood sugar drop during exercise?
Your muscles use glucose for energy, which often lowers blood sugar during moderate exercise.
Why does weightlifting sometimes raise my blood sugar?
High-intensity exercise can trigger stress hormones such as adrenaline, causing your liver to release glucose.
Should I eat before exercising?
It depends on your blood sugar, the type of exercise and how much insulin is active. Your diabetes team can help you work out what’s best for your routine.
What’s the best exercise for Type 1 diabetes?
There’s no single best exercise. Walking, cycling, swimming, resistance training and many other activities can all be beneficial. The most important thing is finding something you enjoy and can do consistently.
Final Thoughts
Exercise is one of the best things you can do for your overall health, but Type 1 diabetes adds an extra layer of planning.
I’ve stopped expecting every workout to produce the same blood sugar result.
Instead, I focus on learning from each session, spotting patterns and making small adjustments over time.
The goal isn’t perfect blood sugars after every workout.
It’s building confidence so that diabetes doesn’t stop you enjoying being active.
Disclaimer
This is based on my personal experience living with Type 1 diabetes. Always consult your healthcare professional before making changes to your diabetes management.
This blog contains affiliate links which means I may earn a small commission if you make a purchase at no extra cost to you.
This article is based on my personal experience living with Type 1 diabetes. Always consult your healthcare professional before making changes to your routine.