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Cyclic Ketogenic Diet and Blood Glucose, HbA1c, Fructosamine, and Insulin
Brief Summary:
Recently I completed a doing a variation of a cyclic ketogenic diet called the , which basically entails eating strict low carb (less than 30 gm per day) with one 6-8 hr window of massive carb loading per week. At the end of this experiment, before going on a trip to , I had a series of fasting labs drawn.
So far we’ve looked at my:
Now I want to go over the labs reflecting my glucose control.
Fasting Blood Sugar
HbA1c = 5.7% (Normal 4.8 – 5.6)
Estimated Average Glucose = 117 mg/dL
My HbA1c came in at a stable 5.7%! It hasn’t changed one iota since I started measuring it and . I still have concerns with the calculated estimated average glucose of 117 mg/dL, especially since I did an measuring my blood sugars at 17 separate intervals while being in ketosis full time, and my blood sugars never got past 92 mg/dL.
I concluded at the time that:
Low Carb -> Lower Blood Glucose -> Longer RBC lifespan -> Higher HbA1c
I guess the good thing to take away from this is that my HbA1c remained stable despite the addition of the massive influx of carbs on Carb Nites.
Fructosamine
This test is similar to the HbA1c in that it calculates your average blood sugar, except that it reflects values in the prior 2-3 weeks rather than the 3 months that HbA1c calculates. This is because this test measures how much glucose binds to proteins in your blood (primarily albumin) which has a turn over of around 2-3 weeks.
The reason I wanted to get this test is to obtain another marker for my average blood glucose that is independent of RBC lifespan, which would confirm my explanation of why my HbA1c is higher than expected.
Fructosamine = 229 umol/L (Normal 0 – 285)
According to the equations found and :
In a fantastic post by he states that:
A normal fasting blood insulin level is below 5, but ideally you’ll want it below 3. If your insulin level is higher than 3 to 5, the most effective way to optimize it is to reduce or eliminate all forms of dietary sugar, particularly fructose.
So after looking into this I feel confident that I’m not insulin resistant and am pretty happy with these results. The other thing I learned is how off the normal range provided is. This again illustrates the importance of seeking health optimization rather than un-sickness.
CONCLUSION:
After working through this post I’m finally able to pinpoint why I was so bothered by the discordantly elevated HbA1c despite having normal fasting sugars: I was worried that I had an underlying metabolic dysregulation such as insulin resistance, which would then subject me to an increased risk of all the badness that comes with it. Seeing the normal but less than stellar fructosamine results also fed into this concern.
The fact that my fasting blood sugars are so good AND my fasting insulin is in the optimal range indicates that I don’t have an underlying insulin resistance, which is comforting.
This would then support my conclusion of a longer RBC lifespan as the reason behind the elevated HbA1c. I still don’t have a clear explanation as to why the fructosamine levels are discordant with my bloods sugars (perhaps the additional carb nites? maybe the equation is inaccurate? maybe I have a lower turnover of albumin also?)
In the future, rather than checking my HbA1c, I’ll preferentially test my fasting insulin levels as a better marker for cardiovascular risk.
… now if I could just figure out why body recomposition while doing ketosis or cyclic ketosis isn’t coming as easily for me as it is for others…
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