There seems to be a lot of individual variation here, probably based on genomics. For instance, see: https://academic.oup.com/jcem/article/99/2/E384/2537265

If you've already got a DNA report, check out promethase.com. They have an inexpensive tool that can look up all the polymorphisms from your report in SNPedia (essentially a wikipedia for single nucleotide polymorphisms - get the naming pun?) and hand you back an interactive report.

The other option is to use yourself as your own guinea pig, either with a continuous glucose monitor or test strips. Then try various foods and see what happens. I tried the strips (super cheap at Walmart), got numb fingers from all the sticks - and didn't learn anything that wasn't in my report. Sigh.