Glucose Ketone Index Monitoring
Combine blood glucose and ketones into one repeatable metabolic reading
- Difficulty
- Easy
- Time to result
- ~ongoing to results
- Steps
- 5
- Confidence
- 96%
Seyfried describes the Glucose Ketone Index, developed with his students at Boston College, as blood glucose in millimoles per litre divided by blood ketones in the same units. Combining the values was intended to make metabolic monitoring easier than interpreting two separate readings, especially when stress temporarily raises glucose while ketones remain elevated. The method is simple: take paired blood readings, calculate the ratio, record the circumstances, and follow the trend. Seyfried says he uses low GKI targets in his cancer work and makes strong prevention and tumour-growth claims. Those claims are his interpretation in the episode, not established here. The index should therefore be treated as a monitoring measure used with qualified clinicians, never as proof that cancer is absent or controlled.
Origin
Seyfried says he and his Boston College students developed the index while monitoring glucose and ketones in a woman with a brainstem tumour. They wanted one more stable number after stress raised her glucose while her ketones remained high.
Core principles
- 01Interpret glucose and ketones together rather than separately
- 02Use blood measurements for the index described in the episode
- 03Track a trend rather than relying on one reading
- 04Treat the number as a monitoring tool, not a diagnosis or cure
How to run it
- 1
Set the monitoring purpose
Define why the ratio is being tracked and which qualified clinician will interpret it in the wider clinical context.
Pro tip Agree in advance how often measurements are useful.
Watch out A GKI target discussed on a podcast is not individualized medical advice.
- 2
Take paired blood readings
Measure blood glucose and blood ketones at approximately the same time, using millimoles per litre for both values.
Pro tip Record factors such as meals, fasting, exercise, illness, and acute stress.
Watch out Do not assume breath or urine indicators produce the blood-based index described by Seyfried.
- 3
Calculate the ratio
Divide the glucose value by the ketone value to produce the GKI reading.
Pro tip Use the same units and calculation each time.
Watch out A zero or implausible ketone reading makes the ratio unreliable and may require checking the measurement.
- 4
Log the context
Store the ratio alongside the raw readings, time, and relevant circumstances so a single fluctuation is not overinterpreted.
Pro tip Keep the glucose and ketone values as well as the ratio.
Watch out One reading cannot establish a trend or a clinical outcome.
- 5
Review the trend clinically
Discuss repeated readings with a qualified clinician alongside symptoms, medicines, nutrition, screening, and established treatment plans.
Pro tip Ask what decision, if any, the trend should change.
Watch out Do not delay cancer diagnosis or standard treatment because a ratio appears favourable.
In the wild
Seyfried recounts a woman with a brainstem tumour whose blood glucose rose after an argument while her ketones remained at 2.5 millimolar. He says this prompted his group to combine the two measurements rather than react to glucose alone. The example illustrates why the raw values, ratio, and circumstances should be recorded together; it does not prove that the ratio predicts tumour behaviour.
→ A stressful glucose spike was interpreted alongside the simultaneous ketone reading.
Seyfried says Pablo Kelly repeatedly recorded GKI during years of metabolic therapy and surgery for glioblastoma. He associates periods of lower readings with slower disease and higher readings with recurrence, but this remains one complex case with multiple interventions and cannot establish causation or a general treatment effect.
→ The ratio provided a consistent longitudinal record for clinical discussion.
Common mistakes
Treating the ratio as a diagnosis
The index measures glucose relative to ketones; it does not show whether a person has cancer or whether a tumour is controlled.
Reacting to one measurement
Stress, meals, exercise, illness, and measurement error can change either side of the ratio.
Replacing oncology care
Seyfried explicitly says he is not telling diagnosed patients to reject chemotherapy, and the index must not displace qualified assessment or established care.
Is it for you?
Best for
People using clinician-supervised nutritional ketosis who need a repeatable way to discuss glucose and ketone trends.
Not ideal for
Diagnosing, preventing, or treating cancer without qualified medical care, or replacing established screening and treatment.
From the transcript
“divide the glucose in millimolar in the blood by the ketone in millimolar in the blood”
“The most accurate is the blood measure.”
From the episode
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