Although both these books have already been recommended above, I’d like to add that I consider Think Like a Pancreas by Gary Scheiner to be the best D-book written in the history of ever. In our house, it is referred to as “The Type 1 Torah.” If you were stranded on a desert island with only one D-book, this is the one to have!
I also highly recommend the Ragnar Hanas book that Jen recommended. I ended up finally (and almost reluctantly) buying it because one particular D-Mom (who is clearly quite intelligent, knowledgable, and wise about her daughter’s Type 1) on the CWD Forum repeatedly recommended it above all others to every new D-parent. I didn’t give it much thought at first because I already had The Type 1 Bible According to Gary Scheiner and knew I didn’t truly need another D-book. That being said, I have never regretted buying Hanas’s book because children with Type 1 are, in many respects, different “animals” than their diagnosed-as-adults Type 1 brethren. If you are the parent of a CWD, you definitely need this book.
Bottom line: if you can only afford one D-book in your lifetime, get Gary Scheiner’s Think Like a Pancreas. Then (if you are a D-parent), save your pennies and get the Type 1 Diabetes in Children book by Hanas. And I agree with Jen, this book is also “great for plain ol’ adults, too.”