The Babybel cheese also has a good shelf life. You can bring lunch meat or shedded chicken in a plastic container with an icepack. There are lots that come as a set now. Since you’re diabetic, TSA should allow you to bring through liquids, so you could also bring through muscle milk (comes in light, has tons of protein). Also, hard boiled eggs will keep if they are not peeled. I travel 6 to 10 times a year by air and I have definitely been allowed to bring through things that count as “medicine” food is medicine if you are diabetic!