The Effects of Nutritional Ketosis on HbA1c Part 2

HbA1c part 2In part 1, I tried to find a reasonable explanation as to why my HbA1c remained elevated at 5.7% before and after 72 days of nutritional ketosis where I remained in ketosis (documented with blood ketone tests) almost the entire time, and to top it off I had low fasting AM blood sugars (avg of 83 mg/dl).

The most plausible explanation I came across was:

Low Carb -> Lower Blood Glucose -> Longer RBC lifespan -> Higher HbA1c

Even though this explanation made the most sense, at least in my situation, I still wasn’t satisfied and had to prove it to myself.  Other potential explanations I thought of included:

  • Maybe there was a lab error
  • Maybe my glucose is actually bouncing around a lot higher than it is when I measure it in the morning
  • Maybe I’m still eating too much protein leading to increased gluconeogenesis
  • Maybe I’m eating more carbs than I think, since I know that food labels can be way off
  • Maybe there’s something else going on with me (like a glucagonoma) causing me to have a higher glucose throughout the day even though I was eating very low carb and having a normal fasting AM level

Since my lab tests were both done by the same lab, Quest Diagnostics, I don’t think there’s anything else I can do to exclude the possibility of lab error.  I’ll be sure to check my HbA1c at the same lab when I check my labs again which will give me another data point to work with and I’ll update this post once this occurs.

Regarding the last 4 items, they can actually be organized like:

  • Maybe my glucose is actually bouncing around a lot higher than it is when I measure it in the morning.  Potential causes include:
  • Maybe I’m still eating too much protein leading to increased gluconeogenesis
  • Maybe I’m eating more carbs than I think, since I know that food labels can be way off
  • Maybe there’s something else going on with me (like a glucagonoma) causing me to have a higher glucose throughout the day even though I was eating very low carb and having a normal fasting AM level

I pretty much ruled out the first 2 of these explanations by documenting what I ate, which was also pretty in line with my standard meals throughout this whole process.  The last explanation is a little more problematic.  The only way to determine what my blood glucose was actually doing was to test it at regular intervals throughout the day.  My plan was to check my glucose at least hourly, with particular attention being paid to my post-prandial numbers.  I was careful about documenting everything that went into my mouth including beverages (except for water).  I also recorded the times of my exercise for the day.  The graph above shows what my glucose did, but here is the full data set:

HbA1c part 2 data

As you can see by the chart at the top and this data set, my glucose stayed within a nice range between 71 – 91 mg/dl.  The average glucose for the day was 83.5 mg/dl, which is in line with the average from my AM fasting blood glucose over 72 days.  Even my post-prandial numbers didn’t change much at all.

It’s also interesting to see that my blood sugars seemed to go down after drinking green tea.  I’m not sure if it was the green tea that caused it, or if it was the result of my exercise earlier in the day… but it definitely warrants further exploration.

After seeing these results, I feel pretty satisfied knowing that my glucose actually isn’t higher than what’s reflected in my AM numbers, because as I said in my prior post, it wouldn’t make any sense at all.  You can’t be in ketosis and have insulin spikes at the same time… they’re mutually exclusive.

If I wanted to be sure, I could do this again for another full day, but since I pricked my finger 17 times during this experiment, my fingers aren’t too excited about doing that.

Instead, when I next check my labs, along with a HbA1c, I’m going to add a fructosamine test, which calculates the average blood sugar over the past 2-3 weeks by measuring how much sugar sticks to albumin (protein in your blood).  This measure is dependent on the average blood glucose concentration and the amount of albumin, but is INDEPENDENT of RBC lifespan, so hopefully it will be more accurately reflect what’s going on.

But until then, the most plausible explanation regarding my elevated HbA1c while being in ketosis is still:

Low Carb -> Lower Blood Glucose -> Longer RBC lifespan -> Higher HbA1c 

Again, as with all of these n=1 experiments, this explanation and the above results only apply to ME.  Hopefully if others explore these topics there will be more information out there, but until then, this is the best I can do.

I’ll also continue to drink my green teas!

13 Responses to The Effects of Nutritional Ketosis on HbA1c Part 2

  1. jj says:

    If you want to try it again without your fingers hating you, you could try alternate site testing. The Precision Xtra is approved for that. Still… I’d give it a rest for a few days, 17 tests in one day is a LOT and even using an alternate site for some tests, you’ll probably end up doing a few finger stick tests.

  2. Daytona says:

    Actually the outside edge of your pinkies and ring fingers are usually the least sensitive places on your fingers to test. Thumbs and index fingers and the pads of your fingers are the most sensitive. I test regularly and always go for the outside edge of my left pinky, can’t even feel it. But yeah… 17 times in one day deserves a medal and a break! 🙂

    Your BG is amazing, I am quite jealous. I have never heard of the fructosamine test but it sounds like it has potential. I am looking forward to your results!

    • BJJ Caveman says:

      now you tell me!!! after almost 3 months of pricking my fingers daily!

      outsides of my fingers from now on. Since I like to hold the lancet with my left hand… my poor right fingers are the ones that are always getting pricked… I’ve since learned to prick my other hand to even things out.

      Will let you know the fructosamine results in part 3!

  3. […] – A marker I wrote about before (Part 1, Part 2) that reflects how much sugar you’ve been exposed to over the past 3 months.  A metabolism that […]

  4. Matt says:


    Just wanted to thank you for sharing your experiences and results, I have just started testing FBG, you have helped inspire me to get more analytical, keep up the good work 🙂



    • BJJ Caveman says:

      Thanks for stopping by! Always glad to help others out there. Once you discover the beauty of self-experimentation it can be extremely empowering.

  5. Charles says:

    Nice study! I have a somewhat similar experience with A1C. I was diagnosed to have diabetes a couple of years ago. Since then I have been watching my diet and controlling my blood sugar. In May of this year, my A1c increased to 6.3 from 5.9 as previously tested so I started further control of my diet and daily test of my blood sugar level. Since then, my early morning BG has been in the range of 85 to 105 with an average of 92 for the last 90 days, much better than the previous 3 month of 105. However my A1c increased to 6.4 as tested last week, a shocking increase after 3 month diet and lost of 7 lb of body mass in this period. I am 5’6″ tall and now only weight 129 lbs. I think now my RBC lives longer as I am healthier with lower blood sugar levels compare to three month ago. I am glad I found your website when I googled this topic in the morning. Thanks for sharing your detailed study and logical conclusion

    • BJJ Caveman says:

      Glad I could help out!

      If you are more curious you may also want to consider getting your fructosamine checked since it is independent of RBC lifespan!

  6. […] have concerns with the calculated estimated average glucose of 117 mg/dL, especially since I did an experiment measuring my blood sugars at 17 separate intervals while being in ketosis full time, and my blood […]

  7. N says:

    Very nice and helpful experiment! I am wondering that drop in your blood glucose after coffee and tea is due to spike in insulin? Im recently becoming quite suspicious of the caffeine as weight loss inhibitor due to its effect on insulin.

    • BJJ Caveman says:

      I’m not sure the drop in 10-15 is actually significant. It was probably just normal variation.

      I plan on doing a followup experiment to this…. so keep an eye out.

  8. kelly says:

    Yep, same experience… After about 1 year of VLC/MP/HF and continued measurable blood ketones, HbA1C was at 5.6. I check my BG often enough to know that there is no way in hell I’m averaging 115.. RBC turnover definitely changes the number.. Just remember to put everything in context. High carb vs Very Low carb changes almost everything. All of the accepted traditional “risk factors” need to be viewed in the light of the SAD that most everyone has been eating in our recent past.

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