Bardos
You never mentioned initially that you were allergic to anything.
Type 2 Diabetis is a condition you will have to live with ... for life. If you are not on medication I would think that, although serious, it may not perhaps be as serious as it could be. It is a good thing that you are aware of the good foods and the not so good foods but do not let this condition run your life, just learn to live with it. With the exception of specific foods which you may be allergic to, there is no food which is totally banned to a Type2 diabetic. Certainly there are foods which you should try to avoid but the secret is consume food at regular periods and in moderation including alcohol.
If you feel you must take sardines and boiled eggs then I would strongly recommend that you incorporate them into a healthy salad in a bowl with a sealed lid. Alternatively you could always take with you, as I do, fresh salad sandwiches. Absolutely no problem with security.