Exercise Timing Simulator
Explore how exercise, food timing, and insulin interact during and after a workout.
Exercise causes muscles to absorb glucose directly — with or without insulin. That means blood sugar can drop during a workout even if you have no insulin on board. When you do have insulin active, exercise amplifies its effect.
This chart is designed to help you visualize how the timing of food and insulin around exercise changes the blood sugar curve before, during, and after a workout.
Pay attention to:
- What happens when you have a lot of insulin on board at the start of exercise?
- What happens when you eat carbs before exercise without insulin?
- How does the timing of food relative to exercise change the curve?
What's happening here?
Your muscles absorb glucose without insulin during exercise, causing blood sugars to drop even with no insulin on board.
When you have insulin on board while exercising, insulin is absorbed faster than usual, which causes insulin to make blood sugars drop even quicker.
Exercise requires careful balancing of food and insulin:
- Blood sugars naturally lower during exercise, so eating carbs before or during can help prevent lows.
- Insulin action peaks an hour after bolus, so working out 1–2 hours after a bolus will cause blood sugars to drop faster than if insulin was taken 3 hours beforehand.
- Eating before exercise without insulin may cause blood sugars to rise before exercise brings it back down.
Applying this to your own life
When exercising, see how the timing of food and insulin around your workouts changes how your blood sugars react before, during, and afterwards. You can do this by looking at a CGM or testing your blood sugar every 30 minutes.
As you make observations, keep notes on what different times and amounts for both insulin and food result in with different workouts.