Post meal blood test question

[PGW]

Should the post prandial blood test be 2 hours after the first mouthfull or 2 hours after the last mouthfull of the meal?

Seems to be different schools of thought on this (according to the dreaded web!!)

What does everyone think?

 

[Leadinglights]

The rule of thumb is quoted as being 2 hours after the first bite.
However this can be misleading if your meal is a protracted affair but it depends why specifically you are testing. If it is to check out a particular meal or comparing meals being consistent is important.

 

[Dragonheart]

First. That is when the digestive process and insulin and blood glucose response begins. And it keeps it consistent so comparisons can be made.

If you did it from last then that timing since your first mouthful gets very variable and makes comparisons hard and also you have no way of knowing how far into the cycle of digestion/insulin/bgl changes you are each time.

 

[PGW]

The rule of thumb is quoted as being 2 hours after the first bite.
However this can be misleading if your meal is a protracted affair but it depends why specifically you are testing. If it is to check out a particular meal or comparing meals being consistent is important.

I am testing for the affect of particular food.
So this meal takes approx half hour to eat and I have been testing 2 hours AFTER I have finished eating. If I test 2 hours after the first bite would you expect the blood sugar reading to be higher after this 2 hour period as opposed to what I have been doing?

 

[Dragonheart]

I am testing for the affect of particular food.
So this meal takes approx half hour to eat and I have been testing 2 hours AFTER I have finished eating. If I test 2 hours after the first bite would you expect the blood sugar reading to be higher after this 2 hour period as opposed to what I have been doing?

Probably, in many cases the 2hr reading will be higher than 2:30hr you’ve been doing. Effectively your meals have probably looked better than they are I’m afraid.

Typically many foods peak at around an hour and then fall from there until they return to baseline. Ideally you want to mimic a non diabetic response of being back close to baseline by the 2hr mark for most meals. That’s the concept of testing food response in type 2.

A few meals have a slower hit (lower GI, fat heavy or fibre heavy etc) and might still be on the way up for much longer than an hour. Ideally you’d need to keep testing til you see them start to fall and know just how long that takes and overall how long to base line.

 

[Drummer]

I am testing for the affect of particular food.
So this meal takes approx half hour to eat and I have been testing 2 hours AFTER I have finished eating. If I test 2 hours after the first bite would you expect the blood sugar reading to be higher after this 2 hour period as opposed to what I have been doing?

Being consistent is the key, but many high carb foods can be easily digested and so the spike comes fairly quickly. I would suggest testing at half hourly intervals to really check on how a food affects you, but only for the first trial. After that if you decide to try variations in amounts or preparation technique you can use data from the first test as a guide for comparison at the high points.

 

[PGW]

Probably, in many cases the 2hr reading will be higher than 2:30hr you’ve been doing. Effectively your meals have probably looked better than they are I’m afraid.

Typically many foods peak at around an hour and then fall from there until they return to baseline. Ideally you want to mimic a non diabetic response of being back close to baseline by the 2hr mark for most meals. That’s the concept of testing food response in type 2.

A few meals have a slower hit (lower GI, fat heavy or fibre heavy etc) and might still be on the way up for much longer than an hour. Ideally you’d need to keep testing til you see them start to fall and know just how long that takes and overall how long to base line.

Thanks for the reply.
When you say "baseline" does that mean whatever the blood sugar level is before starting to eat a meal irrespective of wether its breakfast lunch or dinner?
And on your point about lower Gi foods etc - would the non diabetic response to these be the same as a diabetic in that blood sugar levels would not return to baseline after 2 hours?
(Tricky bugger this testing lark!!)

 

[Dragonheart]

Thanks for the reply.
When you say "baseline" does that mean whatever the blood sugar level is before starting to eat a meal irrespective of wether its breakfast lunch or dinner?
And on your point about lower Gi foods etc - would the non diabetic response to these be the same as a diabetic in that blood sugar levels would not return to baseline after 2 hours?
(Tricky bugger this testing lark!!)

Yes baseline meaning the pre meal reading, whichever one it is.

personally I find GI a bit of a misnomer as many of the so called low GI items are actually quite high carb and cause quite a spike but the fat or the fibre with the carbs slows it all down a little. Those carbs still all turns to glucose in the end and the overall level stays higher than baseline for longer in exchange for rising a little less high. Think or a long low rise rather than a shorter higher one on a graph. And the difference often isn’t what it’s claimed to be according to my meter. Many others that follow low carb find the same. So that’s a long winded way of saying I included it because officially it’s a thing for causing a slower glucose rise but I think it’s a bit misleading and ignore it myself and stick to low carb items.

 

[Leadinglights]

Yes baseline meaning the pre meal reading, whichever one it is.

personally I find GI a bit of a misnomer as many of the so called low GI items are actually quite high carb and cause quite a spike but the fat or the fibre with the carbs slows it all down a little. Those carbs still all turns to glucose in the end and the overall level stays higher than baseline for longer in exchange for rising a little less high. Think or a long low rise rather than a shorter higher one on a graph. And the difference often isn’t what it’s claimed to be according to my meter. Many others that follow low carb find the same. So that’s a long winded way of saying I included it because officially it’s a thing for causing a slower glucose rise but I think it’s a bit misleading and ignore it myself and stick to low carb items.

What foods are designated as low, med or high GI is determined analytically not how the gut deals with those foods and because everybody's gut bacterial flora can be different something med GI for one person may not be for another. Also the GI of foods can be changed by adding fats and protein. So it really is a minefield. It may be useful for some people. Anthony Worrell Thompson wrote a book the low GI diet which I believe he followed when diagnosed as Type 2 diabetic.