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Fasting BG - what time of day?

D

DannyB

Well-Known Member
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I apologise if this has been asked before.

Is there a particular time of day that one should do a fasting BG (home test)? I have tended to work on the principle that provided it has been 12 hours since I ate/drank it dosn't really matter. ie 8am if I ate last at 8pm, 10am if I ate last at 10pm.

However it occurred to me that BG tends to be higher first thing, ie just after waking as the body gets going. So aren't I always going to get a higher reading if I do my fasting tests really early in a morning. ie isn't a 8am test always going to be higher than a 10am test simply because of the time it was taken (sooner after waking)?
 
Hi

I usually just do it when I get up. Sometimes depending on whether Ive had something to eat pre bed it can be less than 12 hours between them. I do know that the later i leave it in the morning the lower my sugars appear to be so i just figure it will balance itself out in that if they are a bit higher than id like they will continue to drop, and also fast acting insulin part of premix will also be floating about. Luckily dont seem to have been hit by dawn phenomenon yet though still in honeymoon so watch this space

My injection time is same every morning to accommodate work so FBG is usually just before that.

L
 
Fasting test for T1 and T2 have slightly diferent reasons behind them..

Even the T1 fasting test, will be slightly different for different regimes...

For T1's that inject a per-mixed or on a 2 injection a day, there is a need to match carb intake to match insulin injected, so a fasting test is carried out in the morning upon waking, otherwise there is a real danger of putting someone into a hypo situation.

For T1's that use basal/bolus regime with injections or with a insulin pump...

The fasting fasting testing (apart from your normal before breakfast BG) is carried out over a period of 12 hours, at different times of the day, this is carried out to see it the dose or in the case of a insulin pump the basal program is correct and is keep the basal line correct... And you fast for 12 hours depending on what part of the day you're are checking, and you Take a BG every hours, not only to check if your BG is steady but to ensure that you are dropping into hypo, or your BG's are getting too high, these two later ones you would have to stop the fasting and take action to correct.

For T 2's

Fasting tests are normally carried in the morning, as this should show what your normal (lowest level) would be either diet or with medication.. Due to how mainly oral medication works within the body and is mostly taken with a meal, fasting durning other parts of the day really wouldn't effect or change (on a daily bases) the medication side of things...
 
Thanks for the replies.

I should have stated that I was referring to T2.

I have found that if I test at approx 9am/10am I always have a lower result then if I test at 7am/8am (just after rising) even though there is 12 hours of fasting in both cases. That would suggest that there is some kind of BG 'rush' associated with the body 'starting up' again after sleep.
 
Yes the liver is dumping glucose when you rise. It is important to test first thing as this level also needs to be in the acceptable range. Usually if you retire with say 5.2 it can be as high as 5.7 - 6.3 and is influenced by what you ate throughout the day and not just your last meal. Once you have breakfast it should be acceptable after 2hours.
 
I have type2

I've always understood that a fasting blood glucose sample is the one taken at the doctor's surgery when I haven't eaten for 12 hours, which happens to be overnight. The test I do myself first thing isn't the same thing - it's a pre-breakfast one.
That's what I've always interpreted it, and don't 'fast' in the sense of not eating for 12 hours when I test myself. I have fasted overnight, but not for 12 hours like when I have a sample taken at the docs for the HbA1C blood test.

I have no idea if that's right, though.
 
Try an experiment next time you have a blood test due, check your BG as soon as you get up and again at the time you have your official bloods drawn, this might be interesting.

It varies with individuals, some may go up several points in a hour without eating, others don't. My BG has become pretty level except for the postprandials, I suspect due to a major reduction in insulin resistance I no longer get as much variation as I used to.
 
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