The effects of exercise are individual and based on, e.g. the amount of insulin in blood, sensitivity to insulin, physical fitness, the quality and duration of exercise and what is eaten beforehand.
Aerobic exercise, such as cycling, brisk walking, running or swimming typically lowers your blood sugar during and after the exercise.
Anaerobic exercise, such as sprinting, weightlifting or gym training typically raises your blood sugar during or immediately after the exercise. However, your blood sugar can easily drop too low afterwards.
During exercise, you should check the sensor reading roughly every half an hour. For most people, a suitable pre-exercise blood sugar level is 5–8 (-10) mmol/l. Depending on how strenuous the exercise is, you need approximately 20–40 g of carbs per hour based on your individual needs.
Use the sensor to check how suitable the following guidelines are for you.
If your glucose level before exercise is < 5 mmol/l and
the trend arrow points → or ↘, consume 15 g of carbs
the trend arrow points ↓, consume 30 g of carbs
If your glucose level before exercise is 5–10 mmol/l and
the trend arrow points → or ↘, consider consuming 15 g of carbs
the trend arrow points ↓, consider consuming 30 g of carbs
If your glucose level before exercise is 10-14 mmol/l and
the trend arrow points ↓, consider consuming 15 g of carbs
the trend arrow points ↑ or ↗ or →, take a correction bolus insulin dose and wait for the glucose level to drop to ≤ 10 mmol/l
If your glucose level before exercise is > 14 mmol/l and the trend arrow points
↘ or ↓, do not take an additional bolus insulin dose. Instead, wait until the glucose level drops to ≤ 14 mmol/l.