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High Fasting Blood Sugar On Low Carb

High-fasting-blood-glucose-measurements-via-2-glucometersI have been on a Low Carb High Fat (LCHF) diet for over 3 years. Lost 35 pounds and have kept it off during this time frame.
I use a 16/8 fasting regimen and eat 2 meals a day. The amount of carbs I consume on a daily basis is so low it borders on ketogenic. 20 to 30 grams a day, I am almost in ketosis.

I went into the lab on Friday to get my bi-annual blood panel. A couple of hours later, I tested at home on my glucometers, 6.7 mmol/L – 120 mg/dl. WTF. I could not believe it. Have my trusty glucometers let me down?  Is there glucose on my fingers?  Try it again and get the same reading. I have a Contour Next EZ and an ACCU-CHEK Aviva that I mainly use because they are accurate.

Monday, I checked my lab results and was absolutely shocked. My Fasting Blood Sugar (FBS) was 7.0 mmol/L – 126 mg/dl on the Richter scale. Then another shock, my doctor called me to discuss the blood work up. So I made an appointment to see him a few days later.

Why So High?

Why do I have a high fasting blood sugar on a low carb diet? Should I be worried or is there an explanation? Even though, I’m following a low carb diet and starting to understand the irregularities of high blood sugar in a fasted state. For someone that sticks to a low carb diet and has such a high fasting blood sugar, doesn’t mean cheating. There are many reasons for this and other ways to determine metabolic health.

Going back to Sunday, 5 days before the test, my FBS was 5.1 mmol/L – 92 mg/dl. Wednesday 2 days before 5.5 mmol/L – 100 mg/dl and then on Friday, test day 7.0 mmol/L – 126 mg/dl.  So as not to confuse you, blood sugar is the same as blood glucose and glucose.

Dawn Phenomenon and Somogyi Effect

There are  2 common explanations in diabetics for high fasting blood sugar (hyperglycemia) in the morning. The first reason is the Dawn Phenomenon and affects people on a low carb/keto diet. As we sleep hormones become active between 1 and 8 am. Through the process of gluconeogensis the liver breaks down glycogen, (stored glucose) and puts back into the blood system. This is a normal response causing the blood sugar to rise.

The second reason is the Somogyi effect, exogenous diabetic insulin users inject too much insulin before bed. The result is hypoglycemia (blood sugar drops too low) followed by stress and then a blood sugar spike[1].  Diabetic insulin users must be aware of this issue.

Adaptive Glucose Sparing

Physiological insulin resistance otherwise known as adaptive glucose sparing, is not the same as pathologic insulin resistance. Pathologic insulin resistance is higher levels of insulin, also known as hyperinsulinemia. Hyperinsulinemia is associated with obesity, hypertension, metabolic syndrome, type 2, diabetes and many chronic conditions.

People that follow a low carb/keto lifestyle and fasting will have low stable blood sugar. In the morning blood sugar will usually be higher, as the day goes on it will eventually come down. When glucose was available from the abundance of carbohydrates the cells would burn glucose. However on a low carb/keto diet the cells will burn fat for energy instead.

Thus, cells will not need insulin to burn glucose for energy. Excess glucose will be circulating in the blood for organs that need glucose. For example the brain is one of the biggest users of glucose.

Other Blood Measurements

Insulin levels, if your insulin sensitivity is normal and you have a higher fasting blood sugar, means you are good. One measurement is not the deciding factor. Now if your insulin is high and fasting blood sugar is high that is a whole different story. There are of course other measurements that we should consider like HgA1c, triglycerides, hypertension, and HDL. These numbers should all be considered and if they are all low, then something else is going on.

The test we need to investigate is the HOMA-IR.

HOMA-IR stands for Homeostatic Model Assessment of Insulin Resistance. Use the calculator from Dr. Richard Maurer’s site The Blood Code.(2)

On this page there are 2 calculators the first is the HOMA-IR the second is the Heart Disease calculator


On your next blood panel workup have the above tests performed including fasting insulin and fasting blood sugar.  All of the tests are important so get them done. Once you have your fasting insulin and fasting blood sugar plug them into Richard’s formula. Now figure out your insulin resistance, and heart disease risk.


What is cortisol?  Cortisol is a stress hormone secreted from the adrenal glands called glucocorticoids. the adrenal glands sit above the kidneys, and have two areas. The adrenal cortex is one and has several zones that produce cortisol.

Cortisol will be generated from stress and will stimulate insulin and will ultimately affect blood sugar.(3)


Researchers from the Harvard Business school published a report that found workplace stress causes 120,000 deaths in the US. The costs associated are close to $200 billion in health care expenses.

Stress comes in many forms from physical, (fasting); psychological, (worrying); or environmental (air pollution); and will increase cortisol levels.

Metabolic Effects of Elevated Cortisol and blood sugar
– Reduced transport of glucose into cells
– Decreased insulin sensitivity (increased pathological insulin resistance)
– Increase in appetite and carbohydrate cravings

When stressed, the body prepares itself by ensuring that enough glucose is available. Insulin decreases, glucagon and epinephrine (adrenaline) levels rise and more glucose is released from the liver. Growth hormone and cortisol increase, which in turn causes muscle and fat to be less sensitive to insulin. Now there is enough glucose for the body to use.

These hormonal responses to the low blood sugar may last for 6-8 hours and blood sugar may be difficult to control.  Stress in a in a low carber may make your blood sugar increase as was my case.
You will not need any  medications.

So again do not worry about any of the above if you are on a low carb /keto diet.


The CDC reports that up to 70 million Americans suffer from lack of sleep. Worldwide 25 % have this same issue. Lack of sleep will lead to health problems. Most people, about 90 % need between 7 to 9 hours of sleep per day. Surprisingly the other 10 % can do with less.(4)

Problems with our daily lives could be affecting the way we sleep, which leads to stress. You need to get enough sleep. Additionally, one hour of lost sleep can increase cortisol levels by 50 percent and will play havoc with insulin.

Glucometer Accuracy

There are many factors that can affect the reading on your glucometer. If you are not sure take another reading. I use 2 of the most accurate glucometers on the market and as you can see the readings are identical. The Contour Next EZ; and the ACCU-Chek Aviva are highly recommended and simple to use. Furthermore, other factors that can alter reading on your glucometer are soaps or fruits with high amounts of sugar.

You must wash your hands thoroughly with soap and rinse clean with water before you do a blood test.

In Summary

I started doing my taxes Wednesday night and worked on it until Saturday, which accounted for the high stress levels. I though I was going to owe a lot of money so in the end brought it to my accountant. She worked on it for about an hour and I ended up paying a lot less. Next time I will bring it to her with all the paperwork in a shoebox and let her take care of it.

Should I be worried about my high fasting sugar on low carb? Of course not, because my A1c was 5.4 and my fasting insulin was 43 pmol/L or 6.2 mU/L.  My insulin sensitivity is a little over 1 but I am working on lowering it.  My stress level is back to normal until next year at tax time. So let me ask you a question.  Do you understand the difference between physiological insulin resistance and pathological insulin resistance?  Should you be concerned? Let me know in the comments.

Finally, moral of the story, let your accountant do your taxes and you will not have any stress.

I appreciate question, comments and concerns.

Thanks for dropping by and viewing.


  1. The dawn phenomenon and the Somogyi effect – two phenomena of morning hyperglycaemia. Rybicka M1Krysiak ROkopień Bhttps://www.ncbi.nlm.nih.gov/pubmed/21717414
  2.  https://www.thebloodcode.com/calculators/
  3. The Cortisol Connection Diet: The Breakthrough Program to Control Stress and Lose Weight, Shawn Talbott, Hunter House; 1 edition, September. 20 2004.
  4.  Sleep: EXACT BLUEPRINT on How to Sleep Better and Feel Amazing Brain Health, Memory Improvement & Increase Energy,


Recommended Reading (See Recommended Books To Read)

Harper’s Illustrated Biochemistry Thirty First Edition McGraw-Hill Education, Victor W. Rodwell, David Bender,  Kathleen M. Botham,  Peter J Kennelly,  P Anthony Weil, May 18, 2018.

The Blood Code: Unlock the Secrets of Your Metabolism, Dr. Richard Maurer, The Blood Code, March 12, 2014.

The Cortisol Connection Diet: The Breakthrough Program to Control Stress and Lose Weight, Shawn Talbott,  Hunter House; 1 edition, September. 20 2004.

Sleep: EXACT BLUEPRINT on How to Sleep Better and Feel Amazing Brain Health, Memory Improvement & Increase Energy, Brian Adams, CreateSpace Independent Publishing Platform, November 16 2015.

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22 thoughts on “High Fasting Blood Sugar On Low Carb”

  1. I just started a low-carb diet & have been concerned about high blood readings in the AM. I’m so glad to read your information before stopping this diet. I also , eat twice a day & keep my carb intake between 50-60. At this present time I’m taking glimepiride (2mg.) Twice daily. My A1C has been at 6, but I continue to gain weight! I’m praying that a low-carb diet is the answer!

    1. Hello Sally,
      I am not a doctor. Any advice you receive from anyone please make sure that your doctor knows about it. Low carb/keto works for some people but not all, you may have to experiment to find your perfect diet.
      Glimepiride, is a medicine used to treat type 2 diabetes mellitus in adults. It belongs to a group of medicines called sulfonylureas and helps control blood sugar levels in people with diabetes. Specifically, a Sulfonylureas (Insulin Secretogogues). Make sure that you understand the side effects of this medication and that your doctor is aware of any of your existing health conditions.

      Can you provide me with any other readings from your blood panel, fasting blood sugar, fasting insulin, triglycerides, HDL-C, LDL, homocysteine, ALT, AST and GGT.
      Then we can have a look at what you eat and drink, describe a typical week with a breakdown of each meal. Do you drink alcohol?

      Let me know and we can go to the next step.
      Take care.

  2. Thats interesting, I thought blood sugar would be lower in the morning, since you haven’t eaten. But through gluconeogenesis, you get more blood sugar in the morning. Thanks for linking the calculator. That’s very helpful. Thanks for mentioning the importance of sleep. I suffer from lack of sleep, but can’t tell why. I give myself ample time to sleep but just can’t sleep! Like I would be willing to sleep more, but I am up at 4 or 5 am without an alarm or anything. I feel I need more sleep but can’t get it. 

    So are you saying in the end that your higher blood sugar was from stress? Or that it was just a normal human thing to have higher blood sugar in the morning?

    Good article!

    1. Hello Charles,

      Blood sugar is always higher in the morning due to the Dawn Phenomenon or the Somogyi Effect. Lack of sleep is always going to cause stress which will cause cortisol to secrete and ultimately lower insulin.

      If you are really troubled by your sleep try reading the “Exact Blueprint On How to Sleep Better and Feel Amazing Brain Health, Memory Improvement& Increase Energy”. Click on the link at the bottom of my post. We sleep in cycles of 90 minutes and if you could shoot for 6, 7.5 or 9 hours that would be ideal.

      Lastly, I was very stressed due to what I thought I was going to owe in taxes and yes cortisol was high along with my insulin. My blood sugar was high too. 

      Note, you have to look at the overall picture of your body numbers, if ALT, A1c, triglycerides, HDL and fasting insulin are normal, then no need to worry. Any of these markers that are out of wack, you can bet there are other issues.

      Out of curiosity what are your numbers?

      Thanks for dropping by and commenting.


  3. This is such great information.  It’s so funny how we’ve always been taught to avoid fat, and now eating the high (good) fat foods is the way to go with the low carbs.  Boy, it’s hard to give up the carbs, though.  I love bread, so that’s my downfall.  I do eat a lot of good fat like salmon, sardines, avocados, etc.    What we eat dictates everything.  I have so many friends with high blood sugar, and I swear they just don’t get the fact that what they put in their mouths affects their health.  Unreal.

    1.  Hello Babsie,

      I am glad you appreciate the information. My family was brought up on high carbs and low fat and that is why my father died of a hemorrhagic stroke and my brother and I are type 2 diabetics.

      You cannot burn fat on a high carb diet because insulin will always be storing fat. You need to be on a low carb high fat diet so that you limit insulin and can start burning fat.

      As Henry Bieler said and the title to his book Food is Your Best Medicine. 

      I highly recommend this book and you can find it in your library or go to my website and go to the Recommended Books To Read page and link to Amazon or search on Indigo.

      Thanks for dropping by and your comments.


  4. Hi Jimmy,

    Thanks for sharing your experience in managing high blood sugar levels when we are diagnosed with diabetes.

    I am a Type 2 diabetic, and my doctors say A1c testing gives a more accurate picture of the severity of diabetes than blood sugar levels. I thought you might know how to test A1c test from home itself? Would you recommend the A1CNow System?


    1. Hello,

      I have never seen the A1CNow System until you told me about it. I went to the site and from the specs it says it is 99% accurate, which is pretty good. On the other hand, I would not buy it because I get my blood panel done every 6 months.

      Even though I agree with your doctor that A1c is important, it is a measurement of the glucose sticking to red blood cells and measured over a period of 90 days.

      As I mentioned in my post 1 measurement does not mean anything unless you count that against the other tests.

      So as in my case my fasting insulin, triglycerides, HDL, ALT and A1C are all normal, the only marker that was off was my fasting glucose. I was really stressed due to my taxes. Stress, lack of sleep, and diet, all affect glucose and insulin. 

      I consistently have low readings of my fasting glucose and I measure it every other day. 

      Work on getting your markers as I mentioned above down, and you should be good.  

      Let me know if you need some help. Ask more questions.

      Thanks for dropping by and your comment.



  5. This was very useful information. My dad have type 2 diabetes since 2015 and he has been using tons of meds prescribed by his doctors at the Veteran Hospital, sadly, sometimes they send him the wrong meds or they don’t send him ALL the meds he requires. So I could really show him this article because I want my old man to be as healthy as he can, on behalf of him, thank you.

    1. Hello Wilfredo,

      Are all of the meds related to the type 2 diabetes? If the answer is yes, then next question is does your dad want to get off of the meds? 

      My disclaimer make sure you get an OK from your doctor before you stop taking any meds, I am not a doctor and do not prescribe medication of any kind.

      Type 2 diabetes is a dietary disease and a high sugary processed food diet will absolutely cause metabolic issues.

      Obesity, non alcoholic fatty liver disease, insulin resistance, high blood sugar, high blood pressure, high triglycerides,  and low HDL. 

      You can have insulin resistance for years, decades and then a stroke or heart attack hits you before you are diagnosed with type 2 diabetes. Unfortunately, a type 2 diabetic has a 5 x risk for stroke and heart attack.

      Convince your dad to have a look at my site, I have a huge Recommended Books to Read page check that out.

      Let me know how it works out, we can help your dad naturally. 

      Thanks for dropping by and your comments.


  6. Hello; with your illustration about the Sugar level rises on the doctor’s findings could be caused by more than one issue. even when you are fasting and on the Ketogenic diet, you are seeing such reading.

     Have you sat down and discuss the findings thoroughly with your health provider? If you have not, you should find the courage to do so, as the issue could be associated with some other ailments of the body.


    1. Hello Dorcas,

      I am glad to see you are concerned, my fasting insulin, A1c, triglycerides, and HDL are all low. My fasting blood sugar jumped for a couple of days because of my taxes (stressed out). I though I was going to pay thousands of dollars when I should have given them to my accountant.

      She managed to get me down to less than a thousand on my tax return.

      I now occasionally measure my fasting blood sugar it hovers at 5.0 mmol/L – 90 mg/dl. I am not to worried about my blood sugar.  If anything my major concern is my insulin. I am shooting for an insulin sensitivity of around 1.0 or so.

      I am now in a routine where I fast everyday for 16 to 18 hours and eat 2 low carb high fat meals.  No sugar or processed foods. 

      My doctor I am sorry to say does not understand metabolic issues. I had to tell him which tests I should have performed. One thing I will say is he is always taking notes and slowly learning.

      Now that we are talking numbers, what are your blood panel numbers?

      Get back to me.

      Thanks for dropping by and your comments.


  7. Hi Jimmy, 

    I really enjoyed reading your post. I learned a few things as well from this well written post. I’m just shocked at the fact that workplace stress causes about 120,000 deaths. That’s crazy! It’s very important to live a balanced life, even though that seems impossible when you have factors such as work stressing you after hours. Haha. 

    1. Hello Nia,

      Stress, sleep, cortisol and insulin do play a huge factor not just for diabetics but for everyone. I used to spend 2 hours in rush hour every working day for 11 years and just hated the commute. The stress level in the commute was enough to raise cortisol and raise your insulin.

      Find that perfect balance in life and please let me know.

      Thanks for dropping by and commenting.



  8. I read your post as you requested after our back-and-forth on another post. I’m also a type 2 diabetic, but you are way ahead of me in your knowledge base. I was going along, “fat, dumb, and happy” with the regimen of metformin and Levemir that my doctor had prescribed, until my son-in-law told me I should check out intermittent fasting on You Tube. He recommended Dr. Jason Fung and Dr. Benjamin Bickman as two people I should listen to.

    Well, long story short, I learned that taking insulin for type 2 is really not a good idea, since I have too much insulin in my body already. I’ve had a paradigm shift in how I want to treat my illness. I’ve begun a schedule of intermittent fasting from 6 pm to 8 am daily, and from 6 pm Saturday to at least noon on Sundays. I’ve also reduced my carbs drastically and how much I eat.

    I’m just at the beginning of this regimen, and have great hopes for success in reversing my diabetes. I have also reduced my insulin injection amounts, and am contemplating eliminating insulin injections entirely. It’s a bit scary though.

    I have always checked blood sugar. I have never tried to check my insulin levels. From what I learned from the two doctors that I listened to, though, I’m causing myself lots of future problems if I don’t get the insulin, not the blood sugars only, down.

    My last A1C was 6.6, and I was way happy with it. Now that I’m becoming more educated, I won’t be happy until it’s under 5.
    I’ll keep reading your posts. You know a lot.
    I’m Grant

    1. Hello Grant,
      Appreciate you taking the time to write this comment.

      Doctors are in the business to work with Big Pharma to prescribe medicine. The majority of doctors and mine included do not understand nutrition and will tell you to follow the Standard American Diet (SAD). The SAD will absolutely make you unhealthy and insulin resistant. I was on Metformin for a very short period, but every time I took a pill I was always queasy and had diarrhea. So I stopped taking Metformin without telling me doctor.

      I said to myself this cannot be right and became obsessed with reversing diabetes. Yes it took a while and I have experimented on myself trying different foods and different fasts and finally, have a routine. My insulin and blood sugar are in the normal range.

      You need to be self sufficient, if you do not understand something, research it. I have read thousands of articles, beware not all are correct. Make sure you check out the references and citations.

      Do you like to read? Check out my Recommended Books to Read page. A work in progress with some short reviews and some YouTube videos from some of the authors.

      Dr. Fung and Dr. Bickman are good to follow to start, both portray the same messages.

      Please note that if you make a change in anything in your lifestyle let your doctor know, use common sense. Please note, I am not a doctor and do not prescribe medication. My disclaimer.

      I like the idea of your fasting and carb reduction. Stick with it make changes as necessary, cut out sugar and processed foods.

      Make sure on your next blood panel you get triglycerides, HDL, fasting insulin, fasting glucose and ALT added on to your test.

      Lastly, as I said in the post you cannot use one number to determine metabolic or diabetic health. The aim is to get all of your numbers down and become insulin sensitive.

      Thanks for dropping by and viewing.


  9. Thanks for the good information. 

    My father has been suffering from diabetes since 2017. I didn’t know how to care for him at first but now I’m getting used to it. When he gets stressed, cortisol is released and insulin is secreted.

    It could be dangerous because low blood sugar leads to hypoglycemia and could be fatal. So it’s very important for a diabetes patient to control stress. This article explains this important fact very well.

    Thanks for your effort.

    1. Hello Grey,

      Stress reduction is a very important factor for diabetics. People that lead high stressful lives will find it very hard to lower insulin and may remain insulin resistant and diabetic.

      The other important factors are eating a low carb high fat diet, exercising, sleep and lifestyle. The goal is to get off of medication and to lead a drug free lifestyle. 

      Please check out my Low Carb High Fat Diet page for further information and also check out my Recommended Books To Read.

      Thanks for viewing and your comment.



  10. I enjoyed reading through this article. I am Diabetes 2, 60 years young and my levels are way too high.

    I have bookmarked this post and will come back and spend more time on this site as I know you are offering some really great info here and I need to get my levels down as my organs are paying the price.

    Thank you so much for this post and for what your site is all about 🙂

    1. Hello Vicki,

      I appreciate your kind words, not sure if you understand the post. The issue that caused my high fasting blood sugar was the stress of my tax return. Stress caused insulin and insulin kept my blood sugar high. My fasting blood sugar on a daily basis is around 5.0 t0 5.5 mmol/L or 90 to 100 mg/dl.

      I am curious, what kind of blood panel numbers do you have?   A1c, triglycerides, fasting insulin, HDL, ALT, and fasting glucose. 

      What are you doing to take care of your type 2 diabetes? Taking medication? Dieting? Exercising? 

      Thanks for dropping by and reading.


  11. I saw a youtube video the other day on Tom Bilyeu channel. His guest speaker was a doctor (do not remember his name) but he was talking about high blood pressure and high blood sugar, when you do Keto and IF. He mentioned that the numbers are only high right after you eat because of the food you have ingested. It should go down right after you eat. It doesn’t matter if you eat high protein or carbs the body still produces insulin and that is why your blood pressure or sugar are high. Basically he said the same thing that you say.

    I think we should just not to worry too much about the numbers. We should go with how we feel, are we out of breath? Do we have energy? We know our body best and I think we should go from there. I am also following the IF but I do not follow Keto but I do eat very low carbs. I feel good about myself and I have lots of energy. I think everyone should practice fasting.

    1. Hello Nuttanee,

      We are going in different directions here. I totally agree that carbs and protein stimulate insulin. Carbs more than protein as protein is converted to glucose through the liver. Carbs are of course sugar.

      For people that follow a Low carb/Keto diet and intermittent fasting, numbers do matter, but when the fasting blood sugar is out of whack due to stress, cortisol is the problem. The solution is to remove the stress so that your fasting blood sugar will come down.

      Leading a high stressful life will keep your cortisol high and therefore insulin will be high. This will definitely affect insulin resistance and other metabolic issues, for example type 2 diabetes as in my case.

      My fasting blood sugar on Monday was normal and my blood workup fasting insulin was low. Also my A1c was 5.4. Normalized numbers.  

      If I may ask, curious to know, what are your numbers?

      Thanks and appreciate your comments.


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