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oral glucose tolerance test

WS novalidaddress at nurfuerspam.de
Sat Oct 7 15:06:50 EST 2006

Dear Somaiyah,

if I understand your question correctly, you feed your rats with your
extract before performing an OGGT. You expect an increase of the
glucose disposal upon drug administration, but you find a decrease
whereas the control rats perform as expected.

I cannot solve your problem i.e. giving you an answer why this happens,
but I have some thoughts:

1a) the oil could delay the glucose uptake in the digestive system - do
you feed oil to the controls, too? if the extract is of oily nature
itself, then you might use some other oil like vegetable oil or, if
necessary, an inert liquid that is not miscible with water, e.g.
silicon oil of the same viscosity.

1b) alternatively, you might inject the drug i.p. as a mix with
dimethylsulfoxide (DMSO) or, if possible, use DMSO to obtain the
extract and inject the controls with the solvent alone.

2) The drug might act in the opposite way or is only "working" in
diabetic subjects. Do you starve the rats for some time (usually
4-8hrs) before the experiments? Beware that the oil itself might
contain lots of calories which increase the glucose load to the
organism, esp. when you use vegetable oil as carrier / solvent.

3) do you have the possibility to make more sensitive experiments i.e.
euglycemic hyperinsulinemic clamps?

For some experimental suggestions on diabetes-related experiments with
rats I suggest Basel Houdali's PhD thesis, available as pdf at

Just out of curiosity: What kind of drug / extract are you working with
and what do you expect: incereased insulin secretion, increased insulin
sensitivity or both?

Best regards,


somaiyah al omari wrote:
> dear sir,
>   i am a biology student doing my B.Sc graduation research about diabetes mellitus, im doing oral glucose tolerance test experiment on normal rats to check the hypoglycemic effect of my plant extract, im giving the rat the treatment and after an hour im giving it 2gm/kg body weight glucose load and then measure blood glucose at 0,30,60,90, 120 and 180min , and i found that the level of glucose increases with time and it doesnt return to starting value which is not expected from normal rats as found in litreature, do you think its due to the oily nature of my extract, plz help me if you have an answer,
>   your sincerely , Somaiyah Al omari
>   thanks.

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