Can storage of food chamge glycemic response?

Yes it can, there was a recent TV program (can't remember which one but will have a search) which showed that pasta leftovers stored in fridge gave a lower BG raise in the volunteers (I assume they were non-diabetics) than freshly made pasta dish.

Michael Mosely on trust me I'm a Doctor, found a few news link

http://www.bbc.co.uk/news/magazine-29629761

http://www.drwf.org.uk/news_uk/rehe...ood-sugar-levels-people-diabetes#.VriCI0vtkpE


http://www.sciencealert.com/heating-your-pasta-makes-it-significantly-better-for-you

There are a few other 'suspects' that can also have an effect.
- exercise levels before and after eating
- amount of fat in the rest of the meal
- amount of fibre in the rest of the meal
- whether your bg was rising, dropping or steady before eating.

For example, the same food taken on its own, on a sedentary, stress free day, will have a very different effect than the same food and same portion size taken with more veg (even low carb veg) and additional fat, before or after exercise, with stress added into the mix.

The conversion of some starchy foods into resistant starch happens when food is cooked and cooled. It was discussed in the media quite extensively a year or so back, but people's reaction to it seems very variable. All the evidence I saw about it referred to non-diabetics, so I am unsure whether we can rely on the same beneficial effects for diabetics. It didn't work for me. (although one of @Scimama 's links looks like it could be about diabetic reactions to resistant starch )

I would also be wondering if today's portion had more, or less of any given component in it. By that I'm thinking, just as an example, if today's had more potato or more beans, or whatever element actually triggers the rise.

I would say it's too complex a jigsaw to pinpoint on one iteration, unless it's something obvious like a bigger portion.