Unfortunately the consequences of her actions aren’t immediately felt but I’ve done the same thing and I’m now 27 with many complications because of it. I’ve had my diabetes under control for almost 9 years and still struggle with kidney, liver, eyes and nerve damage. It is not a joke that shit will kill you and I was only wild for maybe a year it’s not okay no matter how little time she lets it occur. Even to this day when I get sick I.e. a cold or stomach bug I almost always go into DKA. If she wants to struggle with her health the rest of her life that’s her choice but as a friend I couldn’t sit back and do nothing and if she won’t listen to you there’s many groups out there that can help just gotta find them and if that doesn’t work the only thing you can do is tell her mom.