I got tested for pre-diabetes last year and tested negative, but my blood sugar drops/ rises suddenly when I eat a lot of sugar. I respond better to a paleo-style diet, mixed with low GI, and low histamines.
What helped me process foods better was adding digestive enzymes before large meals, and also inositol, which has been proven to help with PCOS issues.
I think it's normal for your blood sugar levels to drop and rise accordingly, as your body balances itself out after ingesting a lot of sugar. I don't advocate digestive enzymes long-term, as your body can become dependant on them for digestion.