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Old 07-28-2011
dr.muhamad's Avatar
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Question glucose Oral vs IV

hello every body
i have a question regarding glucose and insulin levels in blood after oral vs after IV glucose
can anyone help?
the thing made me crazy is that
dr.fisher in kaplan vids said that glucose levels rise more if u give oral glucose vs IV glucose
like how can this happen??
did he made a mistake in saying that??
any explanations?
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Old 07-28-2011
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I agree

No he didn't make a mistake!

One of the GI Hormones is Glucose-dependent insulinotropic peptide (GIP) and it has 2 functions; Exocrine (decrease GI acid secretion) & Endocrine (increase Insulin release). Its released from the K cells in duodenum & jejunum and is stimulated by ORAL glucose, fatty acids & amino acids.

So basically, when you give an oral glucose dose it is absorped more rapidly than an IV glucose dose coz of the direct action of GIP (increased insulin = increased glucose absorption).
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Old 07-28-2011
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Default

thx
but what is confusing me is :
if u give something IV its bio-availability is 100% like if u give 5 grams glucose IV,,u get 5 grams in ur blood in one second..
but if u take this 5 grams in your GI it takes time to get in blood and i dont think its 100% bio-availability
so can u explain it to me please

thanks again
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Old 07-28-2011
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Default Incretins

This is a very important concept in current medicine - especially in diabetes care.

As Hope2Pass and Dr. Fisher mentioned - it is not an issue of bioavailability. In short - and the scientific research paper that talks about this is about 20 years old now - what happens is your body releases hormones called Incretins in response to the sensing of an ORAL glucose meal. The two incretin hormones we talk about are GIP (as mentioned above) and GLP1 (Glucagon like peptide -1) These two hormones together cause increased insulin secretion and decreased glucagon secretion from the pancreas.

If you give IV Glucose, there is no release of Incretin hormones and therefore the release of insulin is much lower.

GIP and GLP1 are very short acting hormones and their A number of therapies try to increase the amount of time that GIP and / or GLP is around in the body therefore increasing the amount of insulin that is released as a result of a meal. There are synthetic GLP-1 analogues such as Exenatide and Liraglutide (Byetta and Victoza - brand names respectively) and a whole bunch of drugs that inhibit the enzyme that breaks down GLP1.

The enzyme that breaks down GLP1 is called DDP4 and the drugs that target this method of increasing insulin secretion are called DDP4 inhibitors. Members of this class include -Saxagliptin (Januvia), Sitagliptin (Onglyza) and the recently US approved Linagliptin (Tradjenta) - US Brand names in brackets.

I suggest you get familiar with the incretin mechanism... I think it's a very important topic in current primary care medicine and since it only works when the body takes in a meal the side effects of these drugs are minimal so they are rapidly becoming first line diabetes type 2 therapy after or with metformin.


Hope that helps - here are a couple of references:

http://en.wikipedia.org/wiki/Incretin

http://en.wikipedia.org/wiki/Dipepti...se-4_inhibitor

http://www.ncbi.nlm.nih.gov/pubmed/3896898

and the websites for the various drugs I mentioned above.
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