What Happens to Your Blood Sugar When You Run, Eat, and Stress Out? My Experience with Dexcom One Plus Blood Sugar Monitor

I have just finished a personal experiment using the Dexcom One continuous glucose monitor (CGM) to track how my blood sugar responds to different foods and activities while following a low-carb lifestyle. Initially, I planned to monitor for a full 10 days, but I had to stop after 6 days due to difficulty sleeping with the device. As a side sleeper, I found it uncomfortable when pressure was applied to the monitor, which is an important takeaway for anyone considering using a CGM: choose a placement on your body that allows you to sleep comfortably.

Key Findings: Food and Blood Sugar Response

One of the most fascinating aspects of this experiment was confirming that my low-carb lifestyle effectively stabilises my blood sugar.

After fully low-carb meals, my glucose levels remained under 5.9 mmol/L, even post-meal.

Certain foods, containing moderate carbohydrates, caused slight increases. For example:

Aubergine, kiwi, and a low-carb bread containing rehydrated oats (5.5g carbs) resulted in a temporary rise to 6.2-6.4 mmol/L about 30 minutes after eating which is still well below the 7.8 mmol/L threshold for non-fasting glucose 

Balmoral chicken with haggis—one of the higher-carb meals I very occasionally consume—caused only a mild increase to 5.9 mmol/L, which was a pleasant surprise.

I also drank red, rosé, and white wine with my meals, and none of these caused any significant blood sugar spikes.

Exercise and Unexpected Blood Sugar Spikes

While my meals generally had minimal impact, I did notice significant spikes related to physical activity and stress:

Moderate yoga sessions led to an increase in fasting blood sugar to 6.4 mmol/L, which is a normal response to exercise.

Running had the most dramatic effect: My blood sugar spiked to 12.5 mmol/L after a 5K run. Since I am new to running and have not trained for high-intensity workouts before, I suspect my body wasn’t fully adapted. After the run, I experienced extreme hunger, similar to the effects diabetics report when their blood sugar drops rapidly. I couldn't shake the hunger until I had both breakfast and lunch within two hours.

Anxiety also impacted my blood sugar: I rarely experience anxiety attacks, but I had one due to concerns about how my lack of sleep might affect my driving. During this episode, my blood sugar spiked to 7 mmol/L, which highlights how stress alone can have a measurable effect on glucose levels.

Final Thoughts & Future Plans

This experiment was incredibly insightful and reinforced my confidence in my low-carb approach. I learned how different foods, exercise, and stress affect my body beyond just nutrition. I plan to repeat this experiment in the future, particularly to see if my body adapts better to running over time. However, next time, I will be extra careful about where I place the CGM to ensure it doesn’t interfere with my sleep.

If you're considering using a CGM, my advice would be to think carefully about sensor placement, be aware of potential non-food-related spikes, and embrace the learning experience. It’s a fascinating way to gain real-time insights into your health!