eating more carb with exercising

[millenium]

Avoiding taking the 20-30 g extra carb may well be more effective though?

Once in a while my dad may want to eat outside meals. Even with less portion of noodle, the carb will be 20-30g over his carb limit. I am thinking if it is still possible for him to eat those and walk around (maybe shop around) for 30 mins and have his post two hours blood glucose still within 8.0?