What Does a CGM Actually Tell You? [And Why Most People Misread the Data]

Most people look at CGM numbers and think they’re seeing the truth.
They’re not.

A CGM does not show judgment. It shows patterns. Misunderstanding these patterns is why many people feel confused, anxious, or stuck.

What a CGM Actually Measures

CGMs measure interstitial glucose, not blood glucose. Interstitial fluid is the liquid that surrounds tissue cells and provides nutrients. The distinction is important because interstitial glucose measurements reflect glucose trends in the body and may differ from blood glucose levels. This matters because:

• There is a lag (usually 5–15 minutes)

• Readings reflect trends, not instant values

Your CGM works best as a directional decision-making tool, not a scorecard. You might notice a steady rise in glucose levels after lunch. This pattern can inform your decision to adjust your meal, perhaps by increasing fiber or reducing carbohydrates, to see whether the trend changes. The same goes for physical activity. If you notice a drop in glucose levels after a walk, it might encourage you to integrate more walking into your routine. By focusing on patterns like these, you can make informed decisions to optimize your health.

What CGMs Do Extremely Well

• Show how food interacts with your body

• Reveal stress and sleep effects

• Expose recovery and overtraining issues

• Highlight metabolic flexibility (or lack of it)

Why People Misread CGM Data

• Obsessing over single numbers

• Ignoring trend arrows

• Comparing themselves to others

• Reacting emotionally instead of analytically

The BioFit Perspective

Data without interpretation creates noise.
Precision coaching turns that noise into insight.

Want to learn how to actually use CGM data? Start by identifying a consistent time each day to review your trends, such as when you wake up or after meals. Watch how your body reacts to specific foods and activities. Try making small adjustments, such as adding a short walk after meals, when you notice patterns. To learn even more, start with the Precision Starter Lab™.