Hi there, am a pastry chef and a type 1 diabetic, don't despair! you will be able to eat chocolate and yummy things, you just have to be aware of what you're eating, count it and have insulin accordingly.
Type 1 diabetics can eat what everyone else can eat as long as they eat in conjunction with proper insulin. However, they should consume a healthy diet, of slow digesting carbohydrates. Things like pastries will raise his blood sugar quickly, and could cause him to go high if hes not careful, not to mention the other negative aspects of that style of eating. I would encourage him to eat fruits, vegetables and lean meats so that he may maintain a healthy diet, that will also be easier on his blood sugar response.
type 1 diabetes is forever. You will not be able to eat everything you want as much as you want any more, without thinking about it.
However, as you learn to use insulin properly you will be able to eat well. But you will learn to count carbs, and match your insulin to this.
I recommend the book "Think Like a Pancreas"and "Üsing Insulin".
Dark chocolate can be part of your diet.