Biometrics like blood glucose (or blood sugar) and blood ketones can provide immediate and ongoing feedback for people following a keto diet. However, there are disadvantages to relying on one independently of the other.
The glucose ketone index (GKI) is a simple calculation that can make it easier to understand these numbers together and is thus considered a more accurate reflection of your body’s true metabolic state. Let’s take a more in-depth look together at the glucose ketone index, how to measure it, why it matters, and factors that can affect your GKI numbers and values.
What Is the Glucose-Ketone Index?
The glucose ketone index (GKI) is a useful tool that reflects the ratio of blood glucose levels to ketone levels. It offers insight into how your body is metabolising energy and how deep you are in ketosis.
Ketosis is a natural metabolic state in which the body shifts from using glucose for energy to utilizing ketone bodies. (1) This energy primarily comes from stored fat, which serves as an alternative fuel source instead of carbs.
There are varying degrees of ketosis, with fasting and carbohydrate intake being two key factors that affect your level of ketosis. Monitoring your GKI can help you understand the effects of ketosis on your body and guide your dietary and fasting efforts.
A lower GKI suggests deeper ketosis and a greater reliance on fat for fuel. This is when all of those amazing keto-based benefits, such as improved mental clarity and better energy levels, will start to kick in.
A higher GKI level indicates that your blood glucose is relatively high compared to your ketone levels. In other words, you are not in deep ketosis or even close to reaching ketosis at all.
Optimally, you’ll want to aim for a GKI of 6.0-9.0 if you want to undergo mild ketosis and don’t have any underlying medical conditions.
For accuracy, it’s best to test glucose and ketone levels regularly. This not only confirms that you’re in ketosis but also ensures that your body continues to metabolize fat efficiently.
How to Calculate GKI
To calculate your glucose ketone index (GKI), you’ll need a few specific supplies and follow certain steps to ensure an accurate reading.
Supplies Needed
To calculate your glucose ketone index level, you will need:
- A testing device capable of testing both glucose and ketones
- Alcohol wipes
- Lancets
- Glucose and ketone testing strips
Step-by-Step Instructions (With Calculator)
After you have gathered the necessary equipment, it’s time to begin the actual GKI calculation process.
1. Make sure to plan to test your GKI 2-3 hours after eating. This is considered the best time to check your glucose-ketone index. It’s important to note that testing too soon or too long after eating to test may affect your results.
2. Use your testing device to check your glucose and ketone levels. Make sure to follow the manufacturer’s instructions for your testing device.
3. Make a note of your glucose reading and ketone reading by writing them down in a journal or on a note on your phone.
4. Calculate your GKI using one of the following formulas, or plug your data into a glucose ketone index calculator:
- Standard GKI formula: (Glucose in mg/dL ÷ 18) ÷ Ketones in mmol/L = GKI
- If your glucose reading is already in mmol/L: Glucose in mmol/L ÷ Ketones in mmol/L = GKI
Enter your blood glucose in (mg/dL) or (mmol/l) *
Enter your your blood ketones *
5. Finally, interpret your results using a GKI values chart. We have one listed below that you can use.
Interpreting Your Results
Once you have completed your test, this table can help you interpret your GKI results:
| GKI | Interpretation | Best for |
| 9.0 or greater | Not in ketosis | N/A — this level indicates that you’re not following a keto diet or only recently started |
| 6.0–9.0 | Mild ketosis | Weight loss and optimal health |
| 3.0–6.0 | Moderate ketosis | Metabolic conditions like type 2 diabetes, insulin resistance, and obesity |
| 1.0–3.0 | Therapeutic ketosis | Dietary management/treatment of cancer, neurological diseases, and chronic inflammatory diseases |
| 1.0 or less | Highest degree of therapeutic ketosis | N/A — this level is generally only attainable under strict, medically supervised ketogenic diets |
Factors That Can Impact GKI
Various factors can influence your glucose and ketone levels, which in turn can impact your GKI. These factors include: (2, 3, 4)
- Amount of food you eat in a single sitting
- Dehydration
- Diet
- Fasting status
- Health status/medical conditions
- Hormonal changes
- How recently you’ve eaten
- How recently you’ve exercised
- Macro composition
- Recovering from an illness
- Sleep quality
- Stress levels
- Total calorie intake
- Use of certain medications
- Use of exogenous (supplemental) ketones
Since all of these can affect GKI, it’s best to check and monitor your GKI under similar conditions and circumstances every time.
Why All of This Matters
Many people who follow a low-carb diet are interested in knowing their level of ketosis, as this will help indicate the benefits of ketosis they may experience. Some advantages of knowing your GKI include:
- Athletic performance: Many athletes experiment with nutritional ketosis or supplemental ketones for optimal performance and increased endurance. Knowing your GKI may be an invaluable tool when it comes to combining athletics with ketosis.
- Fasting: Your GKI can help monitor fasts. You can even use it to determine when you enter ketosis and set a target for breaking a fast.
- Weight loss: Knowing your GKI can help you determine if your body is becoming more efficient at burning excess fat, which can help with weight loss.
- Insulin resistance: Ketogenic diets may help improve insulin resistance. Checking your GKI can help in monitoring metabolic health if you have type 2 diabetes, polycystic ovary syndrome (PCOS), or other health conditions associated with insulin resistance. (5, 6)
- Improved focus and mental clarity: By providing a stable and efficient energy source for your brain, ketones can enhance cognitive performance and support long-term concentration. What’s more, new research shows that combining nootropics with a ketogenic diet can help maximize mental function and concentration. (7)
- Neurological disease: Ketogenic diets have been used for decades for neurological disorders like epilepsy. In these cases, a therapeutic level of ketosis is often required. By going keto, you may also help reduce your risk of neurodegenerative diseases like Alzheimer’s disease or Parkinson’s disease. (8, 9)
- Cancer: Therapeutic ketosis may be helpful for certain types of cancer. Often, a healthcare team will strictly monitor these cases. An early study even shows that ketosis may help to inhibit tumor cell and cancer cell growth. (10)
- Longevity and overall wellness: A low level of nutritional ketosis may be optimal for longevity and overall health. (11) So, even if you don’t have more defined health goals, you may want to check your GKI occasionally.
Learn More: Gluconeogenesis: What It Is and Why You Shouldn’t Fear It On Keto
FAQ
How often should I test my GKI?
According to a 2015 study, if you’re using GKI for the management of a severe condition such as brain cancer, you should ideally measure GKI twice a day, 2-3 hours after you’ve eaten a meal.
If you’re not managing a serious health condition, you might want to scale back on testing, especially as glucose and ketone testing strips can add up in cost. If this is the case, try to check your GKI once a week, making sure to test it on the same day of the week, at the same time, and after the same meal.
Make sure you consistently track your progress so you can get a good idea of your overall progress as the weeks go on.
What should my GKI be for weight loss?
The ideal GKI for weight loss is between 3.0 and 9.0. If you are looking to lose a large amount of weight or have obesity or other chronic health conditions, a low GKI level may benefit you, as it indicates a deeper state of ketosis.
However, if you are only trying to lose a small amount of weight and have no other underlying health conditions, a GKI from 6.0 to 9.0 is the ideal range to aim for.
How accurate are glucose readings for GKI tracking?
The accuracy of glucose readings can vary depending on the device you are using to test them. For the most reliable results, it is generally advised to have your blood drawn at a lab.
What is a normal blood sugar level when in ketosis?
A normal blood sugar level when in ketosis would be between 70-90 Milligrams per Deciliter.
Is the keto diet dangerous?
The keto diet can be safe and healthy, as long as you follow a ketogenic diet that is rich in whole foods. If you keep your meals balanced, follow a keto-friendly meal plan, control your carb intake, and maintain an overall healthy lifestyle, you’ll be able to maintain ketosis and improve your health in a number of ways.
Should ketogenic metabolic therapy become the standard of care for glioblastoma?
Glioblastoma is a brain cancer that hasn’t seen major treatment breakthroughs in over 100 years. The usual approach involves surgery, radiation, and chemotherapy, but these can make it easier for tumors to grow by increasing fuels like glucose. (12)
That being said, recent research has come to light that ketogenic metabolic treatment (KMT) may be a practical treatment option. By participating in KMT, glucose is reduced, and ketone levels are boosted.
This change in levels is considered safer for the brain and could help stop tumor growth without harming brain function. However, more research is needed to confirm this treatment as a viable option for this specific type of brain cancer.
Kickstart Your Keto Journey
The glucose ketone index (GKI) is a powerful tool for helping you on your journey to better health. Whether you’re aiming for a gentle shift or a more therapeutic state of ketosis, understanding your GKI can help you tailor your approach to meet your individual goals.
We here at Perfect Keto have tools and resources that can help you achieve long-lasting results and show you just how easy and beneficial keto can be.
If you would like help figuring out the right amount of fats, carbs, and proteins you need to meet your goals, our Keto Calculator can help.
Read Next: Glycogen Storage Disease: Causes, Types, And Treatments