I'm not bashing Subway. I've always enjoyed a sub. But yesterday the office ordered in. I had a 6" cold cut with lettuce and tomato. Before the meal i was at 5.1 after the meal i was 10.3. I though it was wrong so I tested on the other hand. It was 9.8. So i guess Subway is off the list. I might try just a salad next time to see how that goes. BTW that was on a 9 grain bun which is suppose to be better.
Even a tuna 6" sub has approaching 40g of carbohydrates in it from the bread alone. I am a little surprised that your glucose numbers weren't even higher. http://subway.co.uk/menu/subs/classic/tuna.aspx
Now you know what bread does to you - not just Subway breads! Maybe the size of the bun didn't help? When I used to eat normal bread I could generally manage 1 slice of seeded bread, but certainly not 2 slices, so portion control is very important. Good idea to stick to salad next time.
The salad is likely to be the better option, but if you feel you must have bread, then I'd be inclined to leave the top off and make an open sarnie. Usually Subway provide plenty topping, so that would likely be filling enough?