I would take snacks with you always. In my work bag as well as my lunch I have a couple or three or more small snacks, nuts, dried fruit, fresh fruit and so on. I normally have a snack mid morning, then lunch then a snack mid afternoon. Doing this keeps your levels constant thoughout the day, no highs, no lows. I work particulary long hours, have a home made porridege/meusli breakfast and a proper meal with plenty of green veg when I get home at night. I'm diet only and average 5.5 whenever I do check my blood.