I worked with a guy who had diabetes since he was a child, I think he was once the youngest person in England to be diagnosed and he was almost religious like with his eating schedule and breaks, he was upfront with the company about when and what he needed per work day and he was taking care of himself well with regard to his diet, although he did smoke and drink..
My mother in law does both, or at least did smoke and now she smokes at work and we caught her out.. but diet is something else completely she just doesn't eat at any particular time, only when she feels ill, about the only thing she does do (sometimes) on time is her injections..
Pain in the bum as I said, happy to help but only when people help themselves.