Agree with the previous posts and a lot depends on what your diet was like before diagnosis.
I cut out all all the obvious stuff, sweets, biscuits, chocolates, sugary drinks, jams and marmelades, buns, cakes, things like mars bars etc and probably reduced my carb intake by more than 50% at a stroke.
I then discovered, by testing, that things like white bread, white rice, mashed potatoes etc were also spiking me, so I cut them out.
I settled on rye bread, brown rice, wholewheat pasta and starches like couscous, quinoa, pearl barley and boiled new potatoes and reduced my usual portion size for each. So, I probably reduced my carb intake massively though, by some people's standards, I have quite a carby diet. Importantly though, these are mostly more complex carbs with a lower glycaemic index.