Many cyclists start their day by checking fasting glucose. If the number looks high or low, they worry about what it means for training. But here’s the truth: a single morning glucose reading doesn’t define your fitness, fueling strategy, or performance. What matters far more is the pattern of glucose throughout the day, especially during rides.
Why Glucose Matters for Cyclists
Glucose is your body’s fuel for endurance. Stable glucose means steady energy. Spikes and crashes mean fatigue, poor recovery, and performance drops. Morning glucose is just one data point in a 24-hour cycle.
For example, you could wake up with a “normal” fasting glucose, but if your levels crash during a ride, you’ll still bonk. On the flip side, a slightly elevated morning glucose might not hurt performance at all if you manage fueling well.
The Limits of Fasting Glucose Tests
Traditional fasting glucose is used in medicine to screen for diabetes risk. For athletes, it doesn’t capture what happens under stress, hard intervals, long rides, or fueling mistakes. Athletes need dynamic data, not static snapshots.
The Power of Continuous Glucose Monitoring (CGM)
This is where CGMs are a game-changer. A CGM shows you in real time how your body responds to meals, rides, and recovery:
- Does your oatmeal breakfast keep you steady, or spike you?
- Do your gels cause a crash after an hour?
- Is your post-ride recovery meal refueling you or leaving you flat?
I coached a 52-year-old rider who thought his glucose was fine because his morning numbers were always “normal.” But his CGM revealed massive mid-ride dips. Once we adjusted his fueling, eating 60-70 grams of carbs every 45 minutes—his performance skyrocketed.
Practical Guidelines
- Don’t overvalue morning readings. Look at patterns.
- Fuel consistently on rides longer than 90 minutes.
- Monitor how different foods affect you. Athletes are highly individual.
Conclusion
Morning glucose is a small piece of the puzzle. What really matters is stability throughout the day and during training. Performance is fueled not by one number, but by patterns and habits.
Want to learn how to use CGM in your own training? My book “Training and Competing with a Continuous Glucose Monitor” breaks it all down in practical steps.