Call your doctor. Since your doctor prescribed the Metformin he/she will provide you with instructions on how to prepare for your test.
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At what time should I take metformin the day before an glucose tolerance exam?
by cookieN, Feb 13, 2011 05:02PM
The thing is that my doctor is measuring my glucose control with medication and medication effectiveness. What I want is to know what my real numbers are without the aid of the medication.
This, because I´ve noticed that the past week I´ve been getting glucose numbers around 70 two hours after meals (with medication). Since they are fine or low, could that mean I do not need the medication?
Metformin has an elimination half-life of approximately 17.6 hours. It is not metabolized, but secreted in the urine.
It takes approximately 5.5 x elimination half life's for a medicine to be cleared from your system, therefore it'll be in your system for that long.
So Metformin will be in your system for 96.8 hours i.e. 4 days (5.5 x 17.6 hours).
http://www.drugs.com/answers/how-long-does-glucophage-metformin-stay-in-system-269979.html
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You must first call your doctor and inform him/her of your intentions to halt Metformin to test you glucose "clean". Stopping without doing so is inadvisable.
I will comment on insulin testing in your other post.
This is what I got from what I read.
a. Half life of metformin is 17.6 hours
b. Metformin is cleared from system in 4 days.
What I don´t understand is how many hours before should I take metformin for it not to effect/vary my blood tests results?
Should I stop taking it 17,6 hours before, or stop taking it 4 days before.
The fact that metformin stays in system for 4 days, does that mean that metformin is still effective????
THANK YOU so much for your detailed response. It is very useful.
You're welcome. Glad to be of help.
"The fact that metformin stays in system for 4 days, does that mean that metformin is still effective????"
As you'll see below, 90% is eliminated during the first 24 hrs, the remaining 10% takes up to 4 days to flush from your system. Talk to your pharmacist about its lifespan effectiveness after 24 hrs.
Following oral administration, approximately 90% of the absorbed drug is eliminated via the renal route within the first 24 hours, with a plasma elimination half-life of approximately 6.2 hours. In blood, the elimination half life is approximately 17.6 hours, suggesting that the erythrocyte mass may be a compartment of distribution.