Hi, my son was diagnosed at 8 months. He's now had diabetes 4 years. It is very hard in the early days but young children do adapt really quickly. It took me sometime longer but somehow I got to today.
I would expect your daughter to have a very normal and healthy life. Once upon a time diabetes may have meant a premature death but with modern testing and insulin available there is no reason for blood sugars to be far out of the ordinary for any length of time. Your daughter may actually end up leading a more healthy lifestyle because of diabetes than what otherwise could have been the case. None of us can see the future and poorly managed blood sugars can still lead to serious complications as can other factors like smoking/drinking/drugs/obesity etc...
As a parent the biggest change I've made is to always have a packed bag in the car and at home so that we can always go out and stay out as long as we need. I've got food, glucose powder, drink, clothes, wipes, spare meter, spare needles & lancets, hypo kit, spoons and batteries. I have always been quite organised but I am even more so these days.
The hardest times I've faced is when Khaleb is ill as blood sugars can go very high or low depending on the illness. The rest of the time we have a good routine that suits what we do for the week. He's on Levemir twice a day and Novorapid with meals (X3).
I'm happy to answer any questions you might have. I must say I nearly had a break down when Khaleb was diagnosed but that was more due to the fact the diagnosis would never allow him independence because he is also intellectually impaired and I am a single parent.
Hang in there and just take a day at a time.