Glucose And Keto : Everything You Should Know

glucose and keto diet

If you are on a keto diet, one way to measure success is by tracking and maintaining specific blood glucose levels and ketone levels.

Until a few years ago, tracking blood glucose levels was reserved for those with diabetes or prediabetes, but as we continue to understand the importance of balancing blood glucose levels for general health, it has become more mainstream, especially in the keto community.

It’s becoming popular in this community because maintaining optimal blood sugar levels is important for ketosis. When it comes to high-fat, moderate-protein, low-carb diets, the goal is to keep carbohydrates low, which helps keep blood sugar levels low.

Conversely, if your blood sugar levels are constantly rising, your body will not be able to stay in ketosis, which is the main goal of those on a ketogenic diet.

We’ll look at what blood sugar is, how a ketogenic diet affects blood sugar, and how to test your blood sugar and ketone levels.

What is Blood Glucose?

Blood glucose is the amount of sugar circulating in your blood. When you eat food, your blood glucose rises and falls. This is a completely normal process. But how much your blood glucose spikes may depend on the foods you eat. For example, a high-carbohydrate meal will raise your blood glucose much more than a low-carbohydrate, high-fat meal like keto diet.

What does this have to do with anything? Higher than normal blood sugar levels can damage your body and increase your risk of diabetes and heart disease. Doctors even use blood glucose tests to diagnose type 2 diabetes.

How a Keto Diet Impacts Blood Glucose?

When the availability of glucose drops so low that the body does not have enough energy to use, it enters a state called ketogenesis. In this state, ketone bodies are produced from fatty acids and replace glucose as the body’s primary source of energy. We can measure one type of ketone body in the blood, beta hydroxybutyrate (BHB), which would be considered “mild nutritional ketosis” when the BHB is in the range of 0.5 mmol/L – 1.0 mmol/L. BHB levels in the range of 1.0 mmol/L – 3.0 mmol/L would be considered more optimal ketosis.

As you can see, the relationship between ketone bodies and glucose is reversed. You can’t really get a full picture of what is happening to your body unless you also monitor your glucose. 

glucose test

How To Measure Blood Glucose

To quantify your metabolic health, you’ll need to measure blood glucose levels. Common tests include:

  • Hemoglobin A1c (HbA1c): Provides a rough estimate of “average blood glucose” over the past 2-3 months by measuring the amount of sugar stored in the red blood cells.
    • OGTTAn oral glucose tolerance test (OGTT) is performed in the laboratory and involves ingesting a sugar-containing solution and measuring its effect on blood glucose levels.
    • Fasting blood glucose: Your blood glucose after an overnight fast of around 12 hours.
    • Postprandial blood glucose: This is your post-meal blood glucose. It peaks 1 to 1.5 hours after eating. 

Fasting blood glucose and postprandial blood glucose are both simple home blood tests, as long as you have a blood glucose meter. Just prick your finger, insert the test strip, and record your results.

Taking a blood glucose test is an ideal way to see how different foods affect your body. Simply take a baseline reading (at least 3 hours after your last meal), eat a specific food, and then test 1 or 2 hours after eating. You may be surprised at which foods raise your blood sugar (or not).   

Optimal Ketone Levels and How to Measure Them

Ketone levels are important because they are a sign of ketosis. There are a range of ways to test for them, all of which can be done in the comfort of your home.

When it comes to actual ketone levels, the range of target measurements depends on what your goals are for your ketogenic diet.

If you want to lose weight, then a ketone level of 1.0 mmol/L to 3.0 mmol/L is key. When you go from weight loss to maintenance weight loss, your goal can be 0.5 mmol/l to 1.0 mmol/l.

On the other hand, if you are on a ketogenic diet to get more therapeutic results, aim for a ketone level between 3.0 mmol/L and 5.0 mmol/L.

Testing your ketone levels

There are three different types of ketone bodies, but the most common is beta-hydroxybutyrate, which is what most blood ketone tests check for.

There are three common methods of measuring blood ketone levels. These methods include urine strips, blood ketone meters, and respiratory ketone measurements. You can also get a blood test from your doctor’s office.


Blood glucose is the amount of sugar circulating in your blood. The relationship between ketone bodies and glucose is reversed. That is, when the glucose is low, there might be a state of ketosis. The range of glucose target measurements depends on what your goals are for your ketogenic diet. You can test them by three methods.

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