Blood Sugar Reading Help

(Chris Gill) #1

Hi All,

So I’ve been on the keto diet for 3 weeks now and my blood readings have been
week 1 - 6.20mmol/l and 5.70mmol/l
week 2 - 5.10mmol/l and 4.70mmol/l
Week 3 - 5.40mmol/l

Ive eaten less than 25g carbs per day (most of the time less than 15g)
104g protein
129g fat
1700 calories

I have hit my macros each day give or take a few grams here and there.
Should my readings not be in the 0.5-3.0 area by now rather than being higher than in week 2? Am i doing something wrong?


(Bob M) #2

These are blood sugar readings? Taken when?

If they are blood sugar, if you can afford it, I’d take multiple times per day around the same time. Say, 6am, 10 am, 2pm, 6pm, 9pm (or if you use 24 hours, 6:00, 10:00, 14:00, 18:00, and 21:00). Do that say one day per week, then compare weeks.

So many things affect blood sugar that it’s hard to compare without strict time requirements.

I started taking my blood sugar about 3 years or so into my low carb journey. My morning blood sugar is about the same now (7+ years) as it was then. In fact, it might be slightly higher overall, as exercise causes my blood sugar to go up and I’ve been exercising more now.

But my morning blood sugar is way higher than my evening blood sugar. At least 2mmol/l (18 in US units) higher in the morning.

(Chris Gill) #3

I have been taking these readings in the morning before i eat anything - I assumed this would be the best time to take them as the reading would be after a fast?

(Jack Bennett) #4

When you say 0.5-3.0, do you mean the suggested range for nutritional ketosis?

If so, you may be blurring the line between blood glucose measurement and blood ketone measurement. Based on the earlier numbers, it looks like you’re measuring glucose. That could be life-threateningly low if it ever got down to 0.5-3.0 mmol/L (which it is extremely unlikely to do, so don’t worry about that).

This article has a good discussion of nutritional ketosis from a couple of leaders in the field.

(Bob M) #5

I’ve been near the upper range (3.0 = 54). Got a 62 (official, from a lab) after fasting 4.5 days. I’ve seen people get even lower, when fasting a week. Even Shawn Baker now is getting in the low 50s (somehow – not sure how).

But these are special cases.

Normal blood sugar, eating every day, probably won’t get near there, at least for most of us.

But I do think blood ketones and blood sugar might be getting mixed up. They are both in mmol/l if not in the US.

What happens with me is that a higher blood sugar means a lower ketone reading and vice versa. My highest blood sugar/lowest ketones are in the morning, lowest blood sugar/highest ketones in the evening.

But I’ve been doing this 7+ years, so not everyone will get the same results. I used to get 1-3 mmol/l ketones in the morning. Now, never. Even fasting 4.5 days barely gets my ketones up in the morning.

(Bacon enough and time) #6 gives the following table:

Target Levels by Type Upon waking Before meals (pre-prandial) At least 90 minutes after meals (post-prandial)
Non-diabetic* 4.0 to 5.9 mmol/L under 7.8 mmol/L
Type 2 diabetes 4 to 7 mmol/L under 8.5 mmol/L
Type 1 diabetes 5 to 7 mmol/L 4 to 7 mmol/L 5 to 9 mmol/L
Children w/ type 1 diabetes 4 to 7 mmol/L 4 to 7 mmol/L 5 to 9 mmol/L

*The non-diabetic figures are provided for information but are not part of NICE guidelines.

So the readings you are getting appear to be well within the proper range for pre-prandial serum glucose.

(bulkbiker) #7

Those are blood ketone readings for nutritional ketosis not blood sugar readings.
If your blood sugars were 0.5 mmol/l you’d be almost dead.

(Michael - When reality fails to meet expectations, the problem is not reality.) #8

Short answer: no.

Longer answer: Keto is a metabolic normalization process. As I discovered during my own continuous glucose monitor experiment, and others have as well, keto leads to glucose remaining in the normal, healthy range. As pointed out by @MarkGossage directly above very low glucose is not healthy.

(Bacon enough and time) #9

George Cahill showed, however, that what constitutes “very low glucose” may be lower than previously thought. His famous experiment using a hyperinsulinaemic euglycaemic clamp on research subjects, whose ketones were elevated from several days of fasting, showed that under such conditions serum glucose can be driven to levels low enough to normally be associated with hypoglycaemic coma or even death, yet without ill effect. As Dr. Phinney has remarked, the study participants were fine; it was the researchers who were having palpitations.

It must be stated that even the researchers realised, afterward, what a foolhardy and unethical thing it had been to do, but the results are nevertheless highly illuminating.

(Bob M) #10

I was listening to one podcast where there was a husband and wife fasting for a week. They were using Free Style Libre CGMs, and they simply said “low”. By pin-prick monitors, they got results in the 30s.

But I think for normal people eating “normally”, even low carb, 30 is low. And of course if you have any symptoms (shaky, feel bad, etc.), that’s a warning sign.

When I was in the low 60s, I felt fine. And when they were in the low 30s, they felt fine.

(Bacon enough and time) #11

Whether or not you feel okay, is the key. If the only reason you know your blood sugar is low is because you measured it, then you are probably fine.


If I’m converting right those numbers are fine dude.