Bread has a much higher glycemic index than cola, though. White bread is the "100" on the GI scale, and cola is 60 - that's roughly the "sourdough" range.
It depends on methodology how you calculate it. For example this article says that per some methodology cola GI can be 91: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1989668/
Also, I think GI is weight normalized, so you compare 250g of cola with 40g of carbs to 250g of white bread with 120g of carbs.
Also surprisingly for me, pasta had a relatively low impact on my blood sugar.