My wife had gestational diabetes. She had to mesure and log the values and her food. She is from the north of europe and I am from the south europe. Actually, her body gave permutated values between potatoes and pasta. In a same condition (starting G level, same plate, same quantities, same level of activity, same hour, etc), she could eat potatoes without issue, pasta (even whole wheat) was systematically making her GI skyrocket. It was the opposite for me. A tool to mesure your G level is very instructive.