Sweet Corn has a glycemic index of 60. Compare that with the glycemic index of most low carb veggies and it's considerably higher which means it gets digested better than you would think even if the outside hull is left intact. It's the inside of the grain that raises the blood sugar.
An average ear of sweet corn has about 20 grams of carb. In OWL, an occasional ear probably won't do a lot of damage, but use with caution and observe the effect it has on you; whether or not it provokes cravings.