Think its tested on non diabetics (of course, imagine testing the GI of pasta on me, a T1 on insulin! :lol: ). Theory behind it is the lower the GI the less of a response required by your body (ie insulin) to tackle this.Its often cited as good way to manage weight cause excess insulin is liable to cause you to put on weight (hence T2 weight gain, not CAUSE they are overweight traditionally, but because excess of insulin from being resistant to it encourages weight to go on, stay on)
There isnt a Gi table for diabetics, just GI index per se.
Lower Gi hits blood stream slower, and doesnt raise it up as much. I know what you mean about GI in non diabetics (ie, if your pancreas works, does it matter?) but given the prevalence of prediabetes now, along with the general increase in T2 then yes, it might be one way of looking at carbs in our diet. Lots of diabetics use it as a means of controlling bg Im sure, and EVEN dieticians like it.Couldnt comment on specifics of managing T2 with it but low Gi doesnt mean low carb - pasta being point in question,and also rice. Good on the GI table, hell for your bg.
Also, for someone using insulin, a slow rise in bg (even if the spike isnt as high) makes use of insulin a nightmare in terms of the timing of it. Its good in premixed insulin cause you are trying to control spike cause you cant calculate for each meal per se).For basal bolus regime, I dont find it helps as much and had a lovely hypo 50 mins after 'attempting' pasta for the first time in a year.
Ive heard some insulin pumpers say that they avoid Gi when trying to titrate their insulin needs