Summer's considered the best out of the 4 seasons because most people are on summer vacation and they are able to spend quality time with their family without all the snow or cold weather.
While you didn't provide us with a list of foods that Anna is eating or has eaten in the past, her diet would be appropriate for her if she was abstaining from food that has a high glycemic impact (bread, pasta, candy, chocolate) on her body, or just food which contains glucose in general. Both of these are not allowed for diabetics as they might trigger unwanted effects.
