Glucose Ketone Index (GKI)

The glucose ketone index (GKI) is a calculated ratio: blood glucose in mmol/L divided by blood beta-hydroxybutyrate (BHB) in mmol/L. It originated as a proposed monitoring tool in metabolic brain-cancer research, not as a validated score for general health, weight loss, or dietary quality.¹

Medical disclaimer. This article is for general educational purposes only and is not medical advice. It is not a substitute for professional diagnosis or treatment. Always consult a qualified healthcare provider before starting the ketogenic diet or making changes to your diet, exercise, or medication — especially if you are pregnant or breastfeeding, take medication, or have a medical condition such as diabetes, or kidney, liver, or heart disease. See our editorial & medical-review policy.

How is GKI calculated?

Both readings must use mmol/L:

GKI = glucose (mmol/L) ÷ BHB (mmol/L)

If glucose is reported in mg/dL, divide it by 18 to convert it to mmol/L before calculating the ratio. The glucose and BHB measurements should be taken at the same time if a research or clinical protocol requires the calculation.

What does the result mean?

The original 2015 paper proposed GKI as a way to standardize simultaneous glucose and ketone observations in preclinical and early clinical metabolic brain-cancer research. Its proposed bands were hypotheses for that research context. They were not validated treatment thresholds and should not be presented as targets for cancer, epilepsy, weight loss, diabetes, or general ketogenic dieting.¹

A lower number is not automatically better. A ratio hides its two inputs: it can fall because glucose is low, because BHB is high, or both. Those situations have different clinical meanings. Trying to lower GKI through fasting, medication changes, insulin reduction, or progressively stricter carbohydrate restriction can be unsafe.

GKI is not a DKA test

The 2024 DKA consensus does not use GKI. DKA diagnosis requires diabetes or qualifying hyperglycemia, elevated ketones, and metabolic acidosis. Blood BHB at least 3.0 mmol/L satisfies only the ketone component; venous pH below 7.3 and/or bicarbonate below 18 mmol/L establishes the acidosis component.²

Euglycemic DKA can occur with glucose below 200 mg/dL, particularly with SGLT2 inhibitors, pregnancy, reduced food intake, alcohol-related impaired gluconeogenesis, liver failure, or insulin already taken before testing. A ratio cannot rule this out.

Seek emergency care now for persistent vomiting, severe abdominal pain, deep or difficult breathing, confusion, fainting, or marked drowsiness. These signs are especially concerning for DKA with known or possible diabetes, pregnancy, or SGLT2-inhibitor use; do not wait for very high glucose. Do not calculate GKI or wait for another reading before seeking help.

Who needs to track GKI?

Most people do not. Routine GKI tracking has no established role in general ketogenic dieting. If a registered clinical study or specialist-led protocol calls for it, use the study or clinical team's measurement schedule and interpretation. Do not substitute a consumer ratio for prescribed glucose monitoring, a diabetes sick-day plan, laboratory acid-base testing, or oncology care.

Frequently Asked Questions

What is a good GKI?

There is no validated general-health or weight-loss target. Proposed bands came from an early metabolic brain-cancer research framework and should not be generalized to other purposes.

Is a lower GKI always better?

No. A lower ratio can reflect lower glucose, higher BHB, or both, and the clinical meaning depends on the raw values, symptoms, medical conditions, medications, and acid-base status.

Can GKI diagnose DKA?

No. GKI is not part of the current DKA criteria and does not measure metabolic acidosis.

Do I need GKI for a keto diet?

No. Routine GKI tracking has no established role in general ketogenic dieting. Use it only if a qualified clinical or research protocol specifically requires it.

See also: BHB · Blood ketone meter · Ketosis · Ketoacidosis (DKA) · Detailed ketosis vs DKA guide · Full glossary

Works cited

1. The glucose ketone index calculator: a simple tool to monitor therapeutic efficacy for metabolic management of brain cancer — Meidenbauer JJ, Mukherjee P, Seyfried TN, Nutrition & Metabolism. 2015;12:12, doi:10.1186/s12986-015-0009-2 https://pmc.ncbi.nlm.nih.gov/articles/PMC4381907/
2. Hyperglycemic Crises in Adults With Diabetes: A Consensus Report — Umpierrez GE, Davis GM, ElSayed NA, et al., Diabetes Care. 2024;47(8):1257–1275, doi:10.2337/dci24-0032 — August 23, 2026 https://pmc.ncbi.nlm.nih.gov/articles/PMC11272983/

Article history

1. August 23, 2026Updated
2. August 19, 2026First published