Blood Test - How Long Should I Fast For?

[bravejordy]

I'm due to have a fasting blood test at 9.30 tomorrow morning but how long should I fast for? I phoned my doctor's this morning and the receptionist told me I should have nothing to eat or drink (apart from water) after 8.00PM this evening, but a friend is adamant I should fast for 16 hours. My blood test, by the way, is in relation to my diabetes. I have had fasting blood tests before but my friend reckons this "16 hour fasting" is something that has only recently come out and replaced the unreliable 12 hour method (her words, not mine). Can anyone throw any light on this? I'd appreciate any help.

[LazyGun]

No idea where your friend gets the idea that the 12 hour fast is "unreliable". Conventional fasting has always been recommended as between 8-16 hours, with 12 hours being the "standard".

Were it me I would go with what your Doctors surgery says, rather than some friend.

[bravejordy]

Thanks LazyGun, that means I can have another cuppa or two. ;) Seriously though, I would be more inclined to go with what the receptionist told me rather than some friend, but I just wanted to make sure. My friend claims it was her doctor who told about the 16 hour fasting, but in the light of what you wrote regarding the recommended fasting being between 8 - 16 hours, I'm thinking it's possible my friend may have got her wires crossed somewhere.

[JonnyBoy12]

Without a doubt 12 hours at least. I would give it that time as I have done this many times.

[boxtops]

Twelve hours. I have a regular fasting blood tests around 9am, and am always told by both GP and hospital not to have anything to eat or drink (apart from water) after 9pm the previous evening.

[jno]

I've always been told 12 hours (though my tests haven't been for diabetes; I don't know if that makes a difference)

[lcg]

nothing but a little water after 10pm previous evening. i.e. to take meds or just wet the whistle. that is all...x

[Ann]

My BP nurse tells me to fast from midnight (not that I ever have a midnight feast!) ;)

[naomi24]

Don't ask non-professionals. Take your doctor's advice. That's all.

[JonnyBoy12]

What is a BP nurse if you do not mind my asking?

[Ann]

Blood pressure - in our practice we have a nurse in charge of a BP clinic where all patients with high blood pressure go for 6 monthly monitoring.

[boxtops]

Blood pressure?

[Ann]

We have a fasting blood test every year........

[bravejordy]

Thanks for all your replies.

jno: That was my first thought too, whether the fasting times vary depending on what you have.

lcg76: Your post brings me to another question: Should I take my meds while I'm fasting? The reason I ask is because most of my meds have to be taken either WITH or after food and I certainly wouldn't like to take them on an empty stomach.

naomi24: It wasn't actually my doctor's advice but the receptionist's, whom, I might add, has been known to be wrong before today hence the reason for posting my question here. :)

[Sqad]

You don't say what your "meds" are but I would take you meds as usual well before midnight and after you have had your fasting blood test, which should be in the morning.

[bravejordy]

Hi Sqad,

My meds are as follows:-

METFORMIN 500mg - TWO tablets TWICE a day

EPILIM 200mg - ONE tablet THREE times a day

RAMIPRIL 5mg - ONE capsule DAILY

RAMIPRIL 2.5mg - ONE capsule DAILY

LIPITOR 10mg - ONE tablet EVERY OTHER DAY


I did not miss a dose of my tablets yesterday, I simply took them a little earlier than usual so that they wouldn't collide with my fasting, which began at 8.00PM. I will, of course, be taking my morning tablets around 10.00AM, after the blood test, which is pretty much the normal time I'd take my morning meds anyway.

[Sqad]

Brave...........excellent.