so I have 3 kids, 13, 16, 18.
money is tight, and I meal plan, including a nice after school snack for each day.
We have a snack cupboard, and some ground rules.
So anything on this shelf is planned, and the rest of the cupboard is for you to help yourself.
Same goes for other things, there are certain things/place/cupboards that we ask them not to help themselves to, as food is part of meal plans, and other places where they can freely eat.
Plenty of stuff around, bread, biscuits, fruit, crips, soup, bagels, instant noodles, milk etc.
We also ask them not to make themselves a large snack just before dinner, so they still eat their dinner.
17 is too old to be asking every time. It is old enough to make your own decisions about breakfast and lunch and snacks, and still young enough to eat together as part of the family for the main meal.
He needs to manage his own diabetes himself, and it is really common for teens with a health issue to go through a phase of denial, and almost deliberately eat badly, that is really something he is going to have to work through for himself, and innconjunction with his GP/diabetic nurse etc.
I imagine he is on the cusp of moving from children's services to adult services so this might be a good moment for him to check in with the medical professionals and gte them to support him. He is more likely to listen to them.