Is your daughter an adult? If so, whether she is traveling to France or anywhere in the US, it's the same assuming she has Type 2 Diabetes which is what I have. She can order grilled/baked/roasted/sautéed meats, poultry, seafood, fish. She can order non-starchy vegetables. She has probably gone to a nutritionist at one time or another -- she has more freedom than just big salads.
For carbs, whole grain breads/brown rice earlier in the day. Eat lightly at dinner time and maybe have that larger meal in the middle of the day. Avoid white carbs. Avoid breaded cutlets.
For grocery shopping at breakfast, she should do what she does at home. Poached eggs for breakfast over whole grain breads for example. High fiber cereals. If she wants a croissant, maybe have a small or part of one so she can at least enjoy the taste of it without having to eat the whole thing.
EXERCISE. Being visitors, you two could walk 8-12 miles each day which would be fantastic when she sees the results of that walking on her blood sugar tests. Drink a lot of water like she would at home.
If she is a child or has Type 1 diabetes, follow what the doctor advises. If anything, if she is adult, have her consult her nutritionist. If she is a minor, then you do it before your trip.