What kind of flour do you use? Usually it contains sugar too.
Where do you find flour that contains sugar? I've never seen that in NL and a few countries around it.
Maybe they consider all carbs sugar? ~shrug~
What kind of flour has sugar in it? Most flours are a mixture of starches and protein from grinding up a grain. Starches take more work to digest than sugars, so they don't spike blood sugar levels as quickly.
Flours do contain some naturally occurring sugar, usually less than 1%.