GTT

That would be an excellent question to ask the person that gave you this advice. The only thing I've heard is that eating a low carb diet may cause a false positive result on the OGTT.

So, for the standard lucozade providing 70kcal per 100ml the breakdown is as follows
21.8g sugar per 250 ml.

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Their website says something different: "Nutritional Information (per 100ml): Energy: 297kj / 70kcal, Protein: Trace, Carbohydrate: 17.2, Fat: Nil.", which is consistent with the calories you quoted (1g carbs = 4 kcal, so given that it's sugar water you'd expect about 20g carbs per 100ml)

Using those numbers, you'd get 440ml of Lucozade.

Caution: I just read that the NHS, apparently, uses Lucozade in OGTT. I think that's a mistake - it's called Glucose Tolerance Test for a reason and the WHO specfically calls for (page 48 of this report) 75g of glucose or partial hydrolysates of starch to be used. In contrast, table sugar and high fructose corn syrup/glucose fructose syrup is only about 50% BG active glucose with the rest being (differently metabolised) fructose - that's why there used to be quite a lot of "diabetic sweets" made with fructose that wouldn't affect BG much .

In fairness though, Lucozade is rather unforthcoming with that fact - it says "Drink. Think. Do. Glucose" (product page) but you'll need to read the ingredients to see that it's actually made from high fructose corn syrup.

EDIT to add: There seems to have been a recent change in Lucozade - both Wikipedia and an unsourced alleged GSK document suggest that it used to be made from real glucose syrup ("The sole source of carbohydrate (CHO) in Lucozade Sparkling Glucose Drink is glucose syrup (liquid glucose)" in a 2003 GSK document)

The bottle says 175 Kcals per 250 ml and that equals 70 per 100 ml.
It only quotes sugar and that is 21.8g per 250ml.

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Well, 21.8g sugar contains just 82kcal* so the rest is other carbohydrates - as long as there are three or more glucose molecules chained together it doesn't have to be declared as sugar on the label. Short chains of glucose molecules (that's what the "partial hydrolysates of starch" means) should be counted for the OGTT. ]

I'm pretty confident that 440ml contains the right amount of carbs... but as I said, the issue is that a OGTT is designed to be done with glucose, not glucose fructose syrup. If you want it to be accurate, your best bet is probably to use real glucose (which you can get very cheaply from e.g. Boots)

These 2 docs may help
The calculations
https://docs.google.com/viewer?a=v&q=ca ... 0Bz0t-y5Dg

The answer using the 70kc/100ml formula
https://docs.google.com/viewer?a=v&q=ca ... gDVeRDtFQw
Original lucozade is still made with glucose rather than glucose fructose

Carbonated Water, Glucose Syrup (25%), Citric Acid, Lactic Acid, Flavouring, Preservatives (Potassium Sorbate, Sodium Bisulphite), Caffeine (0.012%), Antioxidant (Ascorbic Acid), Colour (Sunset Yellow).

Nutritional Information (per 100ml): Energy: 297kj / 70kcal, Protein: Trace, Carbohydrate: 17.2, Fat: Nil

Oops... Never mind, it's the Lucozade Energy Orange that's made with glucose fructose syrup aka high fructose corn syrup whereas Lucozade Energy Original is made with glucose syrup... Not that you'd be able to tell without reading the small print though

AMBrennan said:

That would be an excellent question to ask the person that gave you this advice.

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Think that was me

I got it from this NHS document https://docs.google.com/viewer?a=v&...5JO73_&sig=AHIEtbTCwSC9ZBJZOKgpHzxvjHW61H6Xpg

which was a link Phoenix gave me months ago. I think its a copy of a WHO document that says the same thing.

The eat more than 150g / day makes sense to me because as one who follows a low carb (60g / day) regime I can ceratinly have days where I eat more than that yet it doesn't touch my BG's as much as I'd expect. If I continue and try the same thing on day 2 then I begin to see the carbs effect me far more.