Aerobic (Endurance) Exercise - The Glucose Never Lies

Dear Dani, Grace and Jude,

Note: This page is advice for Grace, Jude and John. For any other reader, it’s information only. No therapeutic relationship is formed – read this.

This page teaches you how to make reasonable exercise plans for aerobic (endurance) exercise. Exercise at a consistent pace such as; running, cycling, fast walking, swimming and stepping.

This is a deep dive video I made for a Masters Course that shows me teaching how to make plans and then actually doing 40 minutes of rowing. Feel free to skip this if you just want the how to do it., which comes next.

A quick recap from the exercise introduction page.

Why does glucose usually drops during aerobic exercise?

The importance of planning the meal before exercise.

If possible, to observe the Three-hour rule.

Be careful after exercise if you have been at it for 45 minutes or longer.

Dani, I have put the important stuff into a table so you can make plans for Grace and Jude.

Have a look through it and I will do an example for Grace’s swimming lesson.

Always start with the “Starting Plan” row. If the glucose goes high the first time, then use the yellow “Went high first time” row. If the glucose goes low the first time, then the red “went low first time” row. Always remembering The Glucose Never Lies.

Grace has breakfast at 08:00 on a Saturday, 30g carbs on a 1u:15 carb ratio. She has swimming at 09:00 for 60 minutes. She weighs 20kg. She is having 45g carb at lunch on a 1u:15g carb ratio Here is the plan:

Before exercise: Reduce bolus by 50% – so 1unit
During exercise: Check the CGM before and every 20 minutes; at 08:40, 09:00, 09:20 & 09:40 and follow the 20kg mmol/L chart
After exercise: Reduce bolus by 50% – so 1.5units but no basal reduction as exercise in the first half of the day
Review the results:
- If Grace stated in target, continue with the white “Starting plan” row next time
- If Grace went high, follow the yellow “Went high first time” row next time
- if Grace went low, follow the red “Went low first time” row instead

Grace and Jude, I have pulled the international guidance together into a PDF you can personalise carb amounts and glucose targets depending on the CGM you are using. Click on the device you are using and answer a few simple questions and voila!

You will need Adobe to be able to use them, which you can get for a Computer, Android device or Apple device.

Dexcom G6 – Exercise Carbohydrate Calculator

Libre 1 & 2 – Exercise Carbohydrate Calculator

Medtronic – Exercise Carbohydrate Calculator

Dexcom G6 with pump – Exercise Carbohydrate Calculator

Here are all the carb charts that cover from 10-60+kg and both mmol/L and mg/dL -just in case you cannot use pdf’s!

Carbohydrate charts for 20 minutes of exercise with a mmol/L CGM device