High Fasting Bg Level Even After Fasting

onnecar said:

I had a dissapointingly high bg reading today even though I'm on the LCHF diet and had also fasted for 16 hours. It was 5.8. I would have been expecting 5 or below. I'd also just walked several miles with my dog. Can anyone explain why this is? Has this happened to others with fasting rates? I'm a tofi so I don't know if that makes any difference at all.

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What is it normally?
Do you normally fast for 16 hours and take the dog several miles before you test?
Exercise does raise levels initially.

onnecar said:

I had a dissapointingly high bg reading today even though I'm on the LCHF diet and had also fasted for 16 hours. It was 5.8. I would have been expecting 5 or below. I'd also just walked several miles with my dog. Can anyone explain why this is? Has this happened to others with fasting rates? I'm a tofi so I don't know if that makes any difference at all.

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I have been doing intermittent fasting since last Monday, also on the LCHF diet. I have seen a lot of low (for me) results, but I "accidentally" ended up doing a 63 hour fast this week because I am eating when my meter comes into target range, and my readings just didn't come into the range. I eventually broke the fast yesterday morning, as I am eating out tonight, and I didn't want that to be my first meal.

I was surprised to see higher results during this extended fast than some I had the week before eating one meal a day, but I think I may have had a cold this week, as I had a very slight sniffle for a couple of days, and I have read on these forums that colds can make your blood sugars go up.

I am back to a low level of fasting blood glucose this morning and no more sniffles - I will have to see what the next few days readings are like, but at the moment I am swinging towards the cold as a possible reason.

I always have a high fasting blood test result in the morning, around 7.5, as my liver always dumps glucose as I am waking, no matter what i try to avoid it. And during the day it dumps glucose too. It seems to coincide with my hot flushes during the day. But the morning test is always high. No idea why, it just happens.

onnecar said:

I walk 4 to 5 miles every day so nothing new there. This is my first 16 hour fast. Longest I'd been before that was 12 hours. Been on the low carb diet a couple of weeks. I have had a few pleasingly lower rates but though they would be really low after the longer fast and the exercise.

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If you want a true fasting reading, you need to take it before you go walking (and before any other exercise.)
Then take it again when you get home.

When in a fasted state, your liver is likely to kick in with a glucose dump as soon as you start to exercise. It is doing its job - making sure your glucose levels are high enough for the energy you are using.

In any event. 5.8 is a good reading. Rome wasn't built in a day.

onnecar said:

Thank you bluetit that is a very good and logical explanation. That would explain it. I do also tend to have high fasting blood in the mornings anyway, between 6 and 7. Hoping that will go down a little. Is that likely to go down if I continue to fast and diet do you think? I'm still on 3 metformin and the moment and desperately want to be able to stop those, but will need really good bloods before the nurses agree to that.

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Metformin helps a little with morning fasting levels because it helps reduce the amount of glucose the liver produces.

Morning levels are often the highest of the day, and are dependent on the severity of our insulin resistance. Reduce the amount of insulin secreted = reduces insulin resistance = better fasting levels. Exercise also helps with insulin resistance, but reducing carbs is the key.

So does the liver continue to make glucose in the same way after a few months of sticking to around 20g - 30g carbs per day? Where does the glucose come from, unless you're eating a lot of protein and it gets converted? With 2 days of fasting, I've still got a BG of 6 mmol/l first thing and the lowest I've gone is 4.9 - which is not as low as I've been in the afternoons when eating 3 meals a day and snacks.

I've done 2 days so far.. and it's only the first fast I've done for years. There's a phenomenon called "keto flu" which most people get when they go LCHF if they are strict with it. From what I've read, you dump a lot of water and salt when you begin, and adding some bouillion (I'm guessing because of the salt - you can definitely get vegetable ones) to your intake during the first few weeks can really minimise those symptoms - like the headaches. If you're on metformin, you need to be careful of hypos from what I've been advised here on the forum, but I'm testing very regularly, and not finding that I've been anywhere near a hypo so far. I've been following LCHF for nearly 3 months now, with very few stuff ups - although I am suspicious of some food labelling which spiked me even though they claim to be very low carb on the packaging. I really would like to understand what the liver creates the glucose from when you're not eating much in the way of carbs - I think Dr Jason Fung explained that your liver stores about 80g - 100g of glucose.. but how does it keep making glucose if you are being super strict with your carbs?

Incidentally, I found this lectures series by Dr Fung on youtube to be very helpful. It starts here: It's hours of really interesting information presented in a way that the average layperson can understand. I think I need to watch again to fully absorb some of the information. Even though the title is "obesity" there's a LOT of good information there about diabetes.

@onnecar and @MrsGruffy

Headaches are normally a result of dehydration. It is very important to keep the fluids up when fasting and also on low carb. Very important. It is also important to take in extra salt.

Every single person, including non-diabetics, have glucose stores in their liver. It is there for a purpose. Without it we would die of hypos. In times of fasting, between meals, and at other times when our hormones detect we need extra energy, the liver dumps some from its stores. This also happens in non-diabetics. In every one of us. In normal non diabetics, the hormones trigger this release, then trigger the pancreas to secrete insulin to deal with this glucose and push it into our cells for energy. This means the raised glucose levels are brief and quickly used up for energy. In T2 diabetics the system breaks down because when the pancreas secretes the insulin it cannot work properly and gets rejected by the cells as they are insulin resistant. Hence, the liver dumps but the glucose is rejected by the cells and stays in the blood stream. Fatty livers are also a reason why this happens in T2 diabetics.

The only answer is to get rid of the insulin resistance and fatty liver. The liver will always find glucose to store., and when it empties, it fills up again. Imagine if it didn't ...... in times of fasting glucose levels go very low, and without the liver dumps it would just go lower and lower and lower until we became unconscious.

onnecar said:

I had a dissapointingly high bg reading today even though I'm on the LCHF diet and had also fasted for 16 hours. It was 5.8. I would have been expecting 5 or below. I'd also just walked several miles with my dog. Can anyone explain why this is? Has this happened to others with fasting rates? I'm a tofi so I don't know if that makes any difference at all.

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You just have an effective liver providing you with blood glucose ,

It is similar that when I exercise for 5 hours and don’t eat any carbs at all , my blood glucose almost never get under 5.0 mmol maybe partly due to raised adrenaline speeding up the liver

I must be really thick, but I still don't understand how the liver is continuing to make glucose when you keep your carbohydrates down to a minimum. I've read that your body converts from glucose to ketones, and ketone bodies are a completely satisfactory and efficient fuel choice for your body, and are an alternative to glucose (ie when you become fat adapted). So once you've exhausted your glucose supplies, and you're running on ketones, does the liver continue to make glucose, and if so, what is it made from (especially if you're limiting protein, because from what I understand fat can't be converted into glucose)? I've tried to find something scientific about this on google scholar, but everything so far seems to be about fatty liver disease and doesn't seem to cover what the liver is converting to glucose.

I'm definitely going to buy some of these books when I am a bit less povo.