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  1. #1
    Google Junkie nobimbo's Avatar
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    Default Why It's Important To Not Eat Low Carbs Prior to A Glucose Tolerance Test

    This subject comes up from time to time, and I found something that provides support to the suggestion not to eat low carb for 2-3 days prior to taking a Glucose Tolerance Test. Doing so can make your body respond with a sharp spike in glucose and insulin during the test:

    "Impairment of Glucose Tolerance in Normal Adults Following a Lowered Carbohydrate Intake."

    authors: PEY-YU WANG, TAKASHI KANEKO, YUAN WANG, MASATO TAWATA1 and AKIO SATO

    Tohoku J. Exp. Med., 1999, 189 (1)

    "Some normal people are falsely classified as having impaired glucose tolerance (IGT) if they are given an oral glucose tolerance test (OGTT) when their last meal contained very few carbohydrates. In this study, the duration of carbohydrate restriction was extended to one and three days and the relationship between the carbohydrate restriction and the glucose tolerance after an OGTT was examined. Two different groups of normal subjects were placed on high-carbohydrate (80% carbohydrates) and low-carbohydrate (10%) diets before an OGTT; one group for one day and the other for 3 days ....

    The longer the period of carbohydrate restriction, the severer was the glucose tolerance impairment....

    The impairment of glucose tolerance after carbohydrate restriction may be associated with the Randle effect, which is the activation of the glucose-free fatty acid cycle."

    © 1999 Tohoku University Medical Press


    Just want to add that it is recommended to consume at least 250 grams of carbs a day in the 3 days prior to the test:

    The purpose of the GTT is to determine an individualís blood glucose response to an oral load of glucose under standardized conditions. The test should be carried out after a 12 h overnight fast and after having consumed a diet containing at least 250g carbohydrate per day for at least 3 days. The subject should remain at rest without smoking for the duration of the test. The blood glucose level must be measured fasting and 2 h after the oral glucose load dissolved into 250-300 ml of fruit flavored water.

    http://unix.csuchico.edu/~ms34/Introduction.htm

    Linda
    dx pcos 1984, type II diabetes 2001, also hypertension
    Met 2000mg since 2001, started Glucophage XR 4/22/04, then switched to Met ER 6/04; also: multi, Vit. C, Vit. E, B12/folic acid combo, fish oil & borage oil combo, garlic capsules, cinnamon, Vitex, calcium with magnesium/zinc, biotin, CoQ10, selenium,iron
    Other meds: Verapamil and Altace(for blood pressure)
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  2. #2
    Registered User Dubby's Avatar
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    Just curious ... if eating low-carb can cause a spike for the test, couldn't it cause a spike overall?!? Your body doesn't know that you're getting tested. The article says, "The longer the period of carbohydrate restriction, the severer was the glucose tolerance impairment...."
    Couldn't this be a problem?
    Me (36), DH (36), DD (5)

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    Google Junkie nobimbo's Avatar
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    Dubby, that's a good question, and apparently, from the recent reading I've been doing on a diabetic low carb message board, that is exactly what happens when one "cheats" on a low carb plan with high carb foods. It causes significant problems especially for diabetics who take insulin.

    The importance here is that there may be some people who are being diagnosed as diabetic who actually aren't, if they low carb prior to a GTT. That diagnosis is not something to take lightly, and there can be a variety of problems because of it. And for those who have individual health insurance, a diagnosis of diabetes can make getting insurance very difficult, and the rates sky high.

    Linda
    dx pcos 1984, type II diabetes 2001, also hypertension
    Met 2000mg since 2001, started Glucophage XR 4/22/04, then switched to Met ER 6/04; also: multi, Vit. C, Vit. E, B12/folic acid combo, fish oil & borage oil combo, garlic capsules, cinnamon, Vitex, calcium with magnesium/zinc, biotin, CoQ10, selenium,iron
    Other meds: Verapamil and Altace(for blood pressure)
    Started laser hair removal 7/29/03, completed 3/04 (it works!)
    UAE for fibroid 3/24/03 and 3/16/04

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    Registered User Dubby's Avatar
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    Thanks Linda!! You answered my question perfectly.
    Me (36), DH (36), DD (5)

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    Running & Biking Fool! christyz's Avatar
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    Just want to add that it is recommended to consume at least 250 grams of carbs a day in the 3 days prior to the test:
    My goodness that seems high. I eat about 160-180 g/carb or so on the day each week that I have my 5 mile run. I would have to eat everything in sight to get in 250 g. For a non-runner, that would be an even bigger jump in carb intake. Wouldn't that sudden change in eating habits skew the results as well?

    Thanks for this info!
    Christy

    33 yrs, 1 precious hubby, 2 miracle kids, At Goal Wt for 4 yrs, Trygly's down 445 pts, Free Androgen down from 20 to 2, 3 half 'thons ran, 2 mtns hiked, 1 crazy run in the Rockies, 4 forest trail races, profiled in 2 magazines...1 woman determined to kick PCOS butt!

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