what are normal blood glucose and ketone levels?

  • Elevated insulin and blood glucose levels are associated with a wide range of health issues including obesity, mental health, cancer, cardiovascular disease, and stroke.
  • “Normal” blood sugars are not necessarily optimal for long term health.
  • Most people are somewhere on the spectrum between optimal blood sugars and full blown Type 2 Diabetes.
  • Maintaining blood sugars closer to optimum levels is possibly the most important thing you can do to manage your health, reduce body fat and slow ageing.
  • Blood ketones tend to rise as blood glucose levels decrease, though they can vary depending on a number of factors.
  • People who are physically fit and / or who have been following a ketogenic lifestyle for a long period do not tend to show very high blood ketone levels.

what is diabetes?

“Diabetes” refers to a group of metabolic diseases where a person has high blood sugars over an extended period of time.

One in twelve adults worldwide are classified as having Type 2 Diabetes based on this criteria.  Diabetes is expensive.  In 2012 it cost the US a quarter of a trillion dollars in hospital costs and lost productivity [14] and the cost of “diabesity” is forecast to triple by 2050 grow and become a major burden our economy.  Diabesity has even been classed as a matter of economic and national  security (Pompkin, 2013).

Forty percent are considered to be “pre diabetic” and this number is forecast to grow by more than half over the next two decades to 592 million people by 2035. [1]  If you have prediabetes you have a one in two chance of progressing to Type 2 Diabetes within five years.

Related image

Type 2 Diabetes occurs when people become insulin resistant and their liver releases excess glucose into the bloodstream.  The generally accepted blood glucose diagnosis levels for prediabetes and Type 2 Diabetes are shown in the table below.




after meal


% pop







< 100

< 5.6

< 140

< 7.8

< 6.0%


pre-diabetic 100 – 126

5.6 to 7.0

140 to 200 7.8 to 11.1



type 2 diabetic

> 126

> 7.0

> 200

> 11.1

> 6.4%


Approximately ten percent of people classified as “diabetes” have Type 1 Diabetes which is a condition where a person’s immune system attacks the beta cells in their pancreas.[2]  While less common, we can learn a lot from people with Type 1 Diabetes who successfully manage their blood sugars through careful dietary choices optimised to their goals and targetted insulin dosing.

what are the risks?

While the diagnostic criteria defines half the population currently as ‘normal’, normal is far from optimal.

The Hba1c [7] is a test that gives an indication of your average blood sugar over the past three months.  While half the western population has a Hba1c of greater than 6.0% and hence is considered to have prediabetes or full blown Type 2 Diabetes, the risks of stroke, heart disease and and death from any cause start at much lower levels.


The chart shows that the rate of brain shrinkage with age increases with HbA1c.Chrome Legacy Window 22032015 14339 PM.bmp

Increasing HbA1c is also associated with an increased risk of cancer.


These charts show that the risk for cardiovascular disease, coronary heart disease and stroke all increase with HbA1c.  Anti-diabetic medications, even though they reduce your blood glucose levels, don’t help reduce your risk of cardiovascular disease, which is the number one cause of death globally.


The people with a HbA1c of less than 5.0% have a much better chance of delaying the most common diseases of aging.

Keeping your blood sugar under control is possibly the most important thing you can do to manage your health, manage body fat, gut health, reduce your risk of cancer [11] and slow aging, regardless of whether you have been formally diagnosed with diabetes. [12] [13]

what are optimal blood sugars?

If you’re not a diabetic getting your HbA1c checked by your doctor regularly you can use your average blood sugar values from a home blood glucose metre to see how you’re tracking compared to optimal.  Blood glucose metres are available readily online or at your local chemist.  You can pick them up for less than $10.  Higher end ones will also measure your blood ketone levels. [15]

Paul Jaminet notes that the optimal range for blood sugar is between 70 and 100mg/dL (3.9mg/dL and 5.6mmol/L). [18]  Doctor Richard Bernstein recommends an ideal blood sugar of 83mg/dL (or 4.6mmol/L) for Type 1 Diabetics[17]

The conversion between HbA1c and average blood sugar are shown in the table below.  The risk levels are based on the cardiovascular disease data above.  To calculate your average blood sugar simply take the average of all your blood sugar tests – fasting, before meals and after meals.

risk level HbA1c average blood sugar
 (%)  (mmol/L)  (mg/dL)
optimal 4.5 4.6 83
excellent < 5.0 < 5.4 < 97
good < 5.4 < 6.0 < 108
danger > 6.5 > 7.8 > 140

By the time you become “pre-diabetic” with a HbA1c of > 6.0% you’re well into the danger zone and it’s likely that your pancreas has been pumping out high amounts of insulin trying to keep up for some time and you are well and losing the battle of metabolic health.

If you’re exposed to modern processed foods then it’s likely that you are somewhere on the spectrum between optimal and full blown diabetes. [16]

what are optimal ketone levels?

Once you get your head around blood glucose you may come across the ketogenic diet and managing blood ketone levels.  High blood ketone levels are dangerous in someone with Type 1 Diabetes when they have no insulin and very high blood glucose and ketones at the same time (i.e. ketoacidosis).  However lower levels of ketones with normal blood sugars are a sign that you have a good balance between your fat burning and glucose burning metabolisms.

The chart below shows how glucose and ketone values are related for different people with different levels of metabolic health.  In someone with full blown Type 2 Diabetes their blood sugars and insulin levels are high and they struggle to release ketones and body fat stores when they don’t eat so they are driven to eat again.  By contrast, someone who is metabolically healthy has low glucose and insulin levels and will more easily be able to go longer periods without food as their body fat stores can be released easily.

2017-04-17 (11).png

The chart below shows more than one thousand glucose and ketone values from more than 30 people following a low carb lifestyle summed together.  It appears that most people maintain the sum of their blood glucose and ketone levels (i.e. total energy) at around 5.0 to 6.0mmol/L and most of the time their blood ketone levels are not through the roof.  Healthy people (i.e. without Type 1 Diabetes) following a low carb diet typically have ketone levels between 0.4 and 0.9 mmol/L.

It seems that someone who is metabolically healthy will tend to run at a lower total energy because they can more easily mobilise their stored energy when required.  Think of one of our ancestors hiding in a cave.  There is no point in having high levels of energy floating around in his bloodstream all the time.  But when they need to they can quickly mobilise the energy to run away from whatever wanted to eat it.

Image result for caveman running from dinosaur

The table below shows the the ketones corresponding to the different levels of metabolic health, HbA1c, blood ketones and the glucose : ketone index.

 metabolic health HbA1c average blood glucose blood ketones GKI
 (%)  (mmol/L)  (mg/dL)  (mmol/L)
low normal 4.1 3.9 70 > 0.3 1.9
optimal 4.5 4.6 83 > 0.3 3.5
excellent < 5.0 < 5.4 < 97 > 0.3 11
good < 5.4 < 6 < 108 < 0.3 30
danger > 6.5 7.8 > 140 < 0.3 39

The ketone values shown here may even be lower for someone who is active or who has been following a low carb approach for a longer period.  If you’re fasting, your blood ketone levels may be higher, but if you’re active and fasting for multiple days then your blood glucose are likely to be lower.  Unless you’re chasing therapeutic ketosis there is no need to add extra dietary fat to chase higher ketone levels, particularly if your goal is fat loss from your body.

how do you optimise your blood glucose levels?

There are a number of things you can do to reduce your HbA1c, improve your insulin sensitivity and reduce your total energy including:

Someone with Type 1 Diabetes will carefully balance their carbohydrates and insulin doses throughout the day to try to keep their blood sugar within this narrow range.  However this tight blood glucose control is virtually impossible on the diet recommended by the standard diet recommended to people with diabetes which is the Food Pyramid / MyPlate with the foundation of “healthy whole grains”.  Large doses of highly insulinogenic foods require high doses of insulin to try to normalise blood glucose.  And presto!  You’re on a continuous blood glucose rollercoaster.

The continuous glucose monitor plot below shows the typical blood sugar roller coaster experienced by a Type 1 Diabetic.  This style of blood sugar fluctuation occurs to some extents in all of us to some degree, depending on our diet and our insulin sensitivity.

image004 - Copy (2)

Through the use of a low insulin load dietary approach even someone with Type 1 can achieve normal healthy blood glucose levels without resorting to mega doses of insulin.  If they can do it, you can too.

food lists optimised to suit your goal

The table below will help you choose the dietary approach that is most appropriate for you based on your weight loss goals and glucose levels.


average glucose

waist : height


therapeutic ketosis

> 140

> 7.8

diabetes and nutritional ketosis

108 to 140

6.0 to 7.8

weight loss (insulin resistant)

100 to 108

5.4 to 6.0

> 0.5

weight loss (insulin sensitive)

< 97

< 5.4

> 0.5

< 97

< 5.4

< 0.5

nutrient dense maintenance

< 97

< 5.4

< 0.5

post updated: April 2017


[1] http://www.dailymail.co.uk/health/article-2997882/Diabetes-epidemic-400-million-sufferers-worldwide-Number-condition-set-soar-55-20-years-unless-humans-change-way-eat-exercise.html

[2] http://en.wikipedia.org/wiki/Diabetes_mellitus_type_1

[3] http://www.drperlmutter.com/

[4] http://www.primalbody-primalmind.com/about-nora-gedgaudas/

[5] http://drrosedale.com/#axzz3TzvVehTb

[6] http://www.wheatbellyblog.com/

[7] http://www.diabetes.co.uk/what-is-hba1c.html

[8] http://www.amazon.com/Grain-Brain-Surprising-Sugar-Your-Killers/dp/031623480X

[9] http://www.drperlmutter.com/important-blood-test/

[10] http://www.cardiab.com/content/12/1/164

[11] http://freetheanimal.com/2009/02/sugar-feeds-cancer.html

[12] http://chriskresser.com/how-to-prevent-diabetes-and-heart-disease-for-16

[13] http://www.drperlmutter.com/important-blood-test/

[14] http://care.diabetesjournals.org/content/36/4/1033.full

[15] http://www.ebay.com.au/itm/like/251841014229?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=107&chn=ps

[16] https://vimeo.com/52872503

[17] https://www.youtube.com/watch?v=zJGAbZIvRh8

[18] http://perfecthealthdiet.com/2011/11/safe-starches-symposium-dr-ron-rosedale/

[19] http://www.primalbody-primalmind.com/

[20] http://www.dietdoctor.com/lose-weight-by-achieving-optimal-ketosis

[21] https://www.youtube.com/watch?v=Yo3TRbkIrow

[22]  http://www.cardiothoracicsurgery.org/content/3/1/63

post updated: April 2017

33 thoughts on “what are normal blood glucose and ketone levels?”

    1. HbA1c is an approximation of average blood sugars over the last three months.
      So if you’re trying to estimate your HbA1c use all your blood sugar data, both fasting and after meals.


  1. I love your focus on insulin, as I also believe that it is more important than glucose response. However, I would be interested in your opinion of resistant starch, a specific type of dietary fiber that ferments in the large intestine and directly improves insulin sensitivity. Wouldn’t that be more like treating the cause instead of avoiding the symptoms?

    See http://www.resistantstarch.us/health benefits/blood-sugar-benefits/ for the data. We are expecting the United States Food and Drug Administration to rule on a health claim petition that resistant starch helps reduce the risk of type 2 diabetes because it improves insulin sensitivity, especially in individuals with prediabetes. (https://www.regulations.gov/#!docketDetail;D=FDA-2015-Q-2352)

    Not all types of dietary fibers do this. For instance, the cellulose from plant cell walls is a bulking fiber, but is minimally fermented and does not have these effects. The resistant starch information fits with your data, as green bananas, beans, lentils, and unprocessed grains are all rich in resistant starch.


    1. Thanks Rhonda. Reducing insulin load is certainly just one part of the story. A reduction in insulin load also implies and increase in indigestible fiber which is good for the gut (see https://optimisingnutrition.com/2016/05/02/insulin-load-the-greatest-thing-since-carb-counting/). There are lots of low insulin load high fiber high nutrient density veggies to be had (https://optimisingnutrition.com/2015/10/05/ketogenic-fibre/). We’ve got Tim Steele in our Facebook group and there are ongoing discussion about RS. It certainly seems to be an interesting area. Seems to be lots of benefits but possibly some draw backs if you overfeed a narrow range of bacteria that RS address.


      1. RS feeds a wide range of bacteria. See http://dx.doi.org/10.1038/ismej.2014.63 and http://dx.doi.org/10.1038/ncomms7342. It appears to have a keystone species that initiates the breakdown of the starch granule (Ruminococcus) but hundreds of other species are also increased, including Bifidobacteria. If individuals are lacking in Ruminococcus, they tend to be non-responders, but the entire microbiome changes once its fermentation begins.

        I know Tim, and I’ve answered many RS questions for him. I’ve been working with RS for 14 years and have trained hundreds of dietitians and other health professionals on the topic.


  2. No, there are not. The vast majority of the studies used digestible starch as the control. Researchers try to limit the variables in studies so they can draw conclusions from the differences in results.

    A diet with a wide variety of non-starch veggies would contain a little resistant starch but there isn’t way to guess how they would compare.

    I guess I fall back on the fact that starch has always been in human diets so it naturally evolved as a major food for our microbiota.


    1. I’ve got a friend who has just found she has pre-diabetes and has started testing her blood sugars. After meat, veg and potato her blood glucose was 9.0mmol/L. Without the potato, same meal her blood sugar is 5.3mmol/L (my wife with type 1 has a similar but more exaggerated experience). Should they eat more or less potato?


  3. Thank you so much for this blog and the effort you put in to helping others!!! I am type 1 32 years and finding it very hard to gain control over bs levels. Read Dr B’s book and trying to put it all together to gain control. I have been eating lc for 1.5 years and am gaining weight and taking about 42 units a day. On a pump and dex I am going to try using the insulin load to see if it can help. Thank you for all your information


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s