W26 in Diesel? That's really slim
I tried on some Nudies last week and I had the same size as in Diesel, 29. I'd recommend to visit a store and try Nudie, that's the best way. If they don't have the wash you want, you can still order it over the internet afterwards.
Btw, You're from Germany, right? Visit Peek&Cloppenburg, they (in Berlin, don't know about other cities) have a huge selection of Nudies.