Don't forget that it's not so simple as 1+1=2 for everyone. People have to inject different amounts for the same amount of carbohydrate and the time of day can affect results too. The best thing is to take a day when you have no other commitments and monitor your levels a lot so that you can ascertain what is going on with those foods in YOUR body. Note down the relationships at different times of day and adjust accordingly. Also try to eat mid-GI foods. You have to try to match the profile of your insulin with the pace at which your body deals with the carbs. You can check it all out online, but remember you have to be adaptable.