When I was in my early 20s I went from not thinking about diabetes much to suddenly feeling a TON of emotions around it (sadness, fear, anger, overwhelmed). I didn't feel like I had anyone who I could talk to because I felt like the only people who could truly understand were other people with Type 1, and at the time (early 2000s) the DOC didn't exist as it does today. Instead, I searched for and read every book I could get my hands on about diabetes, especially autobiographies by people with diabetes. I think Sweet Invisible Body was the first autobiography I read, and I have a used copy sitting around that I've been meaning to re-read, but never seem to get the time.
A book that stuck with me more than the above is one called Needles. I'm not sure why I remember it more, except that the second chapter literally made me cry uncontrollably. Very few books do that. It's an excellent book, though has some grim parts when it comes to diabetes complications affecting young adults. I've been meaning to re-read that one, too.
Incidentally, it was reading these autobiographies that made me realize I wanted to control my diabetes better, because ALL of the people who wrote them ended up with complications. At the time I had an A1c in the high 8% range, and I realized I really wanted to work on getting that down, which is what eventually led me to the DOC in 2005 searching for other people with diabetes.
Another excellent book (whose prolouge also almost made me cry!) is Cheating Destiny. It's more about Type 1 in a broader sense, but talks a lot about how Type 1 affects someone's childhood years, too.
Though not an autobiography, another EXCELLENT book is The 50 Secrets of the Longest Living People with Diabetes. I love this book because it's inspirational, yet not preachy nor one of those books that just ignores everything that's difficult about diabetes as if it doesn't exist.
I always love book recommendations so am looking forward to others people may have!