CGM Guide for Non-Diabetics: What Your Glucose Data Actually Means

Who Should Wear a CGM?

Continuous glucose monitors were designed for diabetics. In the last 5 years, they’ve become a longevity tool: worn by healthy people who want to understand their metabolic responses to food, exercise, sleep, and stress.

You’ll benefit most from CGM if:

• You have a family history of type 2 diabetes
• Your fasting glucose or HbA1c is in the “high normal” range
• You’re trying to optimise body composition
• You want to understand which foods cause the biggest glucose spikes for you personally
• You’re training for endurance sports and want to understand carbohydrate metabolism

The Metrics That Matter

1. Time in Range (TIR)

The percentage of time your glucose stays between 70 and 140 mg/dL (for non-diabetics). Optimal: above 90% time in range.

Most healthy young adults achieve above 95% TIR. Values below 80% suggest metabolic dysfunction even if fasting glucose appears normal.

2. Glucose Variability (CV%)

How much your glucose fluctuates. Measured as coefficient of variation. CV under 25% is considered stable.

High variability, even within “normal” ranges, is independently associated with cardiovascular risk. You can have normal average glucose but dangerous spikes.

3. Mean Glucose

Your average over the wear period. For non-diabetics, optimal mean is under 100 mg/dL, ideally 80 to 95 mg/dL.

4. Post-Meal Peak

The highest point your glucose reaches after a meal. For longevity:

• Under 140 mg/dL: Excellent response
• 140–180 mg/dL: Moderate spike, watch this food
• Above 180 mg/dL: Significant, reduce portion or pair with protein/fat

What Raises Glucose (That Surprises People)

Stress: Cortisol releases glucose into the bloodstream. A stressful meeting can raise glucose 20–30 mg/dL.

Poor sleep: One night of poor sleep increases next-day glucose variability significantly. CGM makes the sleep-glucose connection viscerally real.

Dawn phenomenon: Many people wake with glucose already elevated (80–100 mg/dL) due to cortisol morning spike. This is normal; alarming values (above 110) are not.

Exercise type: Strength training initially raises glucose (liver glucose dump), then lowers it. Cardio lowers it throughout. Both are beneficial long-term.

The Most Useful CGM Experiments

Wear one for 2–4 weeks and test:

1. Rice vs. sweet potato: Same carb count, vastly different glucose responses for most people
2. Eating order: Vegetables first, protein second, carbs last, typically reduces peak by 20–30%
3. Walking after meals: A 10-minute walk post-meal blunts glucose spikes significantly
4. Sleep quality: Compare nights of 7+ hours vs. 5–6 hours. The glucose difference is striking
5. Alcohol: Raises glucose initially, then causes reactive hypoglycaemia, explains morning fatigue

See also: Stelo vs Lingo, compared from the brands’ pages and FDA notices.