Real-time glucose response
CGM (Continuous Glucose Monitor).
A wearable sensor that streams your glucose every few minutes for two weeks. The only way to know how your body actually responds to your food, your sleep, and your stress.
Prescribed wearable · 14 days · roughly 4,000 readings
Why it matters
A fasting glucose draw is one number from one moment. A CGM gives you roughly four thousand glucose readings in fourteen days, mapped to what you ate, when you slept, and what you did. The pattern is almost always more revealing than the average. Two people with identical HbA1c can have completely different glycemic variability, and variability is what damages tissue over time. The two weeks are also self-correcting: most patients change their eating before the sensor comes off, because the data is impossible to argue with.
Standard glucose testing assumes you are diabetic or trying to rule it out. The reference range is built around that question. A CGM lets me read your glucose against optimal: the tighter band associated with how the body actually performs best, not the loose band that just rules out frank disease. The interventions that move you toward optimal are usually small. Meal sequence. Walking after meals. Stopping late-night snacks. The data makes them stick because you can see them work in real time.
What I read for
Mean glucose. Glucose variability. Time-in-range at optimal thresholds, not the diabetes-care default. Post-meal excursions and how fast they decay. Overnight stability. The personal foods, time-of-day patterns, and stress-glucose relationships that no textbook can predict.
I read a CGM as five separate questions, each one writing a specific change into your Plan:
- What is your real average glucose, not the lagging three-month estimate?
- How tight is the variability around that average? (variability damages tissue more than the mean does)
- Which specific foods spike you, and which ones do not?
- What does overnight glucose look like? (the dawn effect is one of the most useful diagnostic windows)
- How does stress, sleep loss, and exercise change the curve?
What it measures
A CGM measures interstitial glucose every few minutes for the wear period. The downloaded report reads three layers: how high your glucose runs on average, how much it swings, and the patterns that explain those swings in your actual life.
Glycemic control. Mean glucose across the wear period and an estimated A1c derived from it. Time-in-range read against two different targets: the diabetes-care threshold (70 to 140 mg/dL) and the optimal threshold I prefer for non-diabetic patients (70 to 110 mg/dL). Most patients learn their time-in-optimal-range is lower than they expected.
Variability. Standard deviation and coefficient of variation summarize how tightly your glucose holds around its average. Variability matters more than the mean. High variability damages endothelium, drives oxidative stress, and shows up in cognitive symptoms before the average even shifts. A patient with a normal mean but high variability is often the one with brain fog and afternoon crashes.
Patterns. Post-meal excursions (the spike and decay after each meal), overnight stability, and the dawn effect (the morning rise driven by cortisol). The pattern reading is where most of the actionable information lives. The same patient with the same average can have completely different patterns from one wear period to the next, and the patterns change with diet, sleep, and stress in measurable ways.
See all 12 biomarkers
Glycemic control
- Mean glucose (mg/dL)
- Estimated A1c
- Time-in-range 70 to 140 mg/dL
- Time-in-range 70 to 110 mg/dL (optimal)
Variability
- Standard deviation
- Coefficient of variation
- Glycemic variability index (GVI)
- Average daily excursion
Patterns
- Post-meal glucose excursion (1 hr and 2 hr)
- Excursion decay time
- Overnight glucose stability
- Dawn-effect magnitude
Who this is for
A CGM is the right test when glucose response is the question, or when symptoms suggest something is happening with blood sugar that a single fasting draw cannot see.
Common reasons I order it
- Fatigue, brain fog, or mood swings that track with meals or time of day
- Pre-diabetes risk where you want to intervene before HbA1c rises
- Performance work where carbohydrate timing matters (athletes, longevity training)
- Weight loss work, particularly when the diet looks right on paper but the scale is not moving
- Suspected reactive hypoglycemia or post-meal crashes
- Sleep problems that may be glucose-driven (overnight dips, morning spikes)
- Anyone wanting an objective baseline before adjusting carbohydrate intake or meal timing
It is also one of the few tests where the patient often changes behavior before I even read the data. The sensor itself is the intervention.
How collection works
- 1
We decide it is the right test.
A short conversation to confirm a CGM answers your question, and which sensor fits your situation. [NEEDS YOUR INPUT: Note your default Rx (Dexcom G7, Libre 3, or Stelo) and the criteria for picking between them.]
- 2
I send the prescription.
[NEEDS YOUR INPUT: Workflow for filling the Rx. Direct to a pharmacy, mail-order through a partner, or self-purchase with Stelo (which is OTC). Note any insurance considerations.]
- 3
You wear the sensor.
Apply the sensor on the back of the upper arm using the applicator that comes with the kit. The application is quick and essentially painless. The sensor reads continuously for 10 to 14 days depending on the device.
- 4
You log what matters.
You do not need to log every bite, but I will ask you to note meals, sleep, exercise, and any stress events you want me to correlate with the curve. The data is far more useful when I can pair the glucose pattern with what was actually happening in your day.
- 5
We read it together.
At the end of the wear period, you share the report with me from [NEEDS YOUR INPUT: which app: Dexcom Clarity, Libre View, Stelo app, Levels, etc.]. We sit down with it and translate the patterns into specific changes for your Plan: meal sequence, food choices, timing of carbohydrate, walking protocols, and what to confirm on a follow-up wear period.
How to prepare
Preparation is minimal. The goal is to eat and live normally so the data reflects your actual life, not a performance.
Eat and live normally during the wear period: do not change your diet for the sensor. The point is to read your real patterns, not your best-behaved ones.
Note the major events you want correlated: meals (with rough macro composition), sleep windows, exercise sessions, and significant stress. Most apps let you tag events directly in the timeline.
Avoid acetaminophen during the wear period: if possible. High doses can interfere with Dexcom readings. Confirm before stopping if you need it for pain control.
Avoid soaking the sensor for long periods: showers and brief swims are fine. Long hot baths or saunas can loosen the adhesive.
Wear an arm band if you are physically active: to protect the sensor from being knocked off. Most providers offer over-sleeves for athletes.
If you are taking insulin or a sulfonylurea, we coordinate carefully. CGM data can shift medication dosing and that needs to be planned, not improvised.
What you get
The 14-day data exported from the sensor app, plus a debrief with me where we translate the curve into specific instructions for your Plan: which foods to keep, which to drop, when to eat them, how to sequence meals, and the post-meal walking and exercise protocols that flatten the spike. Concrete, not generic.
Most patients change their eating before the sensor comes off, because the data is impossible to argue with. A second wear period 3 to 6 months later confirms the changes are working. Two wear periods a year is enough for most patients to maintain.
Questions
No. The applicator inserts a tiny filament under the skin in a single click. Most patients describe it as a quick pinch or no sensation at all.
Yes. The sensors are water-resistant. Long hot baths or saunas can loosen the adhesive, but normal showering and brief swimming are fine.
Indirectly. Some apps push glucose data to the Watch as a secondary display, but the primary reader is the phone app paired with the sensor. [NEEDS YOUR INPUT: which app you have patients use, and whether Watch integration is part of your workflow.]
[NEEDS YOUR INPUT: Cash-pay cost for a 14-day CGM kit, with and without insurance. Note Stelo as the OTC option if relevant, about $99 for a 28-day starter kit.]
[NEEDS YOUR INPUT: For pre-diabetes or diabetes diagnoses, often yes. For preventive or performance use in a non-diabetic patient, usually cash-pay. Confirm and adjust.]
Once is enough to learn the basics about your personal glucose patterns. Twice a year (a baseline and a follow-up after the changes) is what most patients end up doing. Performance athletes sometimes wear one quarterly around training blocks.
How to order this
Part of the Precision Partnership baseline. Lab fee at vendor cost. I interpret the results into your written Plan.
From the writing