How exercise affects me
Not all exercise does the same thing. Some kinds push your glucose down. Some push it up. Some do both. Once you know which is which, exercise gets far less scary.
Glucose during your run
6.4
mmol/L
Four kinds of exercise
What each kind usually does
Aerobic means your breathing can keep up - you could carry on for a while. Anaerobic means short bursts so hard you are quickly out of breath and need to stop.
Light exercise (stretching)
Your glucose stays steady.
Steady exercise (aerobic)
Walking, cycling, jogging, swimming
Your glucose will often fall.
Your muscles use more glucose for fuel, so levels drop as you keep going.
Think about less insulin, or some carbs, before longer sessions.
Short, hard exercise (anaerobic)
Sprinting, heavy weights, HIIT, competitive sport
Your glucose may rise.
Your body releases stress hormones like adrenaline, which push stored glucose into your blood.
Do not panic - this can be completely normal. Expect a fall later, as you recover.
Mixed exercise (aerobic and anaerobic)
Football, rugby, tennis, basketball, mountain biking
It may go up, down, or both.
These mix steady movement with short bursts of hard effort, so you get both patterns.
Watch your trend arrow rather than the number on its own.
The big question
“I did the same thing - why was my glucose different?”
This is one of the most common questions people ask. There is usually a reason. Lots of things change your glucose at the same time, and exercise is only one of them.
All of these change from day to day. That is why the same activity can give you a different result. It is not you getting it wrong.
Your body
Your day
Your challenge this week
Become a Diabetes Detective
Every time you exercise, ask yourself three simple questions. Write the answers down. You are not trying to be perfect - you are looking for patterns.
What did I do?
What happened to my glucose?
Why do I think that happened?
Every pattern you spot makes the next session easier. That is how confidence grows.
Prefer an app? You can log sessions and see your glucose alongside them in Enhance-d.
Want the detail?
What is going on inside your body
You do not need this to exercise safely. But if you are curious, here is the short version in pictures.
- Glucose
- Insulin - the key that lets glucose into muscle
- Adrenaline
1 · At rest
Glucose stays balanced
Food and your liver top up your blood. Insulin is the key that lets glucose into your muscles to be used or stored.
2 · Steady exercise
Glucose falls
Working muscles pull glucose in by themselves. Insulin already in you adds to that, and your liver cannot top up fast enough.
3 · Short, hard bursts
Glucose rises
Adrenaline tells your liver to release its store, faster than your muscles can use it. Expect a fall later as you recover.
Where your glucose comes fromTwo sources, two stores.
- Your blood gets glucose from your liver and from the food you eat
- It is stored in your muscles (a small amount) and your liver (a lot)
- Your brain can only run on glucose, so your body works hard to keep it topped up
Insulin and glucagonTwo hormones that pull in opposite directions.
- Insulin lowers glucose by moving it into your muscles and liver
- Glucagon raises glucose by telling your liver to release its store
- With Type 1 diabetes you control the insulin side yourself, which is why timing matters so much
Why insulin already in you matters mostIt is the single biggest factor.
- Exercise makes insulin work harder than usual
- So the same dose has a bigger effect when you are moving
- If you exercise within two hours of a mealtime dose, a lower dose often helps