My diabetic boyfriend boyfriend wont take care of himself?!!??!!!?

My boyfriend and I are both 18 and have been dating for 2 years. is a type 1 diabetic he has had it ever since he was 11. he doesnt care that he has it. he hardly takes his insulin and he says he only takes it when he starts to feel dizzy. he has had a few diabetic seizures, been in a diabetic coma once and had diabetic ketoacidosis which are all potentially life threatening, either because he has taken too much insulin or too little, he eats whatever he wants like chocolate, cakes and biscuits and even drinks energy drinks full of sugar like lucozade. his doctor even told him that if he carried on like this he IS going to die! my boyfriend doest care though, he just says 'if it's my time to go then it's my times to go' it kills me inside because I love him so much and I cant lose him but he can be soo stubborn sometimes! what should I do!?!