BG response and GI

[Mark T]

Here is a question, possibly better suited to those with CGM?s. How does the GI of food actually impact your blood glucose levels? Does it just change the point at which the BG hits the blood, or does the amplitude of the BG also change?

From a presentation that has been posted on here before:

This shows the results of BGM monitoring of people on ?normal? meals
http://www.diabetes-symposium.org/index.php?menu=view&source=topics&sourceid=16&chart=18&id=322

This one if a CGM plot following Meal ?A? which was defined as Fast Carbs
http://www.diabetes-symposium.org/index.php?menu=view&source=topics&sourceid=16&chart=30&id=322

Unfortunately there wasn?t a plot for the ?Slow Carbs? meals.

The amplitude of the ?peak? from a normal meal to fast carbs is pretty much the same ? all that happens is the peak occurs sooner.

The general opinion is that the peak should be lower and later for a Low GI food ? but it?s one thing to theorise that and another to be able to show data!

 

[Robster65]

What a cracking question Mark.🙂

Something that I've moaned about for ages is that the insulin (injected or natural) responses are well documented, as are 'average' foods, but since the peak is affected by so many things, it becomes near impossible to match one peak to the other.

Will be watching this thread with interest.🙂

Rob

 

[HelenM]

This study shows the very different glucose responses to hi and low Gi meals with T1 children using CGM and an insulin pump.
The meals were
low GI: 150 g boiled spaghetti, 120 g bolognaise sauce,140 g red apple, 300 ml water to drink (429 cal, 60.1 g carb, GI 34)
High GI: 280 g peeled boiled potato, 120 g bolognaise sauce, 300 g watermelon, 300 ml water to drink (430cal, 57.1g carb, GI 76)

Fig 2 shows the curves were for 2 meals. ( A is the low GI one, B is the high Gi meal; the 3 lines show normal non D controls, T1 children, using a normal bolus, and using a dual wave bolus .

http://care.diabetesjournals.org/content/31/8/1491.full.pdf+html

 

[Mark T]

Thanks Helen for that study.

It was difficult to instantly see the differences between the two plots, so I merged them in GIMP:

The purple Low GI trace is definitely staying noticeably below the High GI trace.

 

[everydayupsanddowns]

Shows the benefit of a dual wave (or manually implemented split dose) with low GI meals too.

 

[Robster65]

Demonstrates nicely that low GI is probably not so good for T1son MDI. I presume with a pump, you could tweak things to nearly match the profile but not sure if there's an injectable insulin that would respond in that way (maybe Apidra?).

Medium GI has to be the target, but how to acheive that in a mixed meal is anyone's guess.

Would the low GI portion temper the high GI or just delay the spike, which is back to Mark's original query.

Rob

 

[Northerner]

...
Would the low GI portion temper the high GI or just delay the spike, which is back to Mark's original query.

Rob

A mixture of foods with different GI can be expressed as GL (Glycaemic Load) and is a refinement of using the GI of foods which may be misleading (e.g. watermelon high GI, but less impact than implied because the portion size would be relatively small.

 

[MeanMom]

Demonstrates nicely that low GI is probably not so good for T1son MDI. I presume with a pump, you could tweak things to nearly match the profile but not sure if there's an injectable insulin that would respond in that way (maybe Apidra?).

Medium GI has to be the target, but how to acheive that in a mixed meal is anyone's guess.

Would the low GI portion temper the high GI or just delay the spike, which is back to Mark's original query.

Rob

As K is on MDI we always try to aim for a medium GI as find this is not so 'spikey'. (We have never used a CGMS so this is from random testing).

We would amend the above low GI meal to pasta tubes instead of spagetti, lentil bolognaise (we dont eat meat but also that adds some low GI carbs to meal) some cheese with the apple and small glass of fruit juice diluted with same amount of water instead of just water.

This is actually the meal we have least 'trouble' with of any but of course would not work for everyone (K tends to digest animal protein quite slowly - maybe because she has so little of it and it is from diary sources and so also quite high in fat?)

So my answer to Marks question would be that in our experience low GI plus high GI in same meal means gradual rise rather than nasty spike. Easier said than done tho' (and dont get me started on Mashed potato😱)

 

[everydayupsanddowns]

...(and dont get me started on Mashed potato😱)

I'm alright with mash as long as I lower the GI with some nice fatty sausages and keep my liver busy with red wine...

 

[heasandford]

is that the answer 'always keep your liver busy with wine' !

 

[everydayupsanddowns]

is that the answer 'always keep your liver busy with wine' !

Well it's an interesting theory... I think we'd need to experiment a great deal and compare notes. 😉