Reddit reviews A Dog Who's Always Welcome: Assistance and Therapy Dog Trainers Teach You How to Socialize and Train Your Companion Dog

A Dog Who's Always Welcome: Assistance and Therapy Dog Trainers Teach You How to Socialize and Train Your Companion Dog was one of the first books I read when I got my puppy. Might be a good starting point for you.

For a great book about socializing a service dog I can really recommend, A Dog Who's Always Welcome. it's geared towards someone who doesn't have experience training service dogs so it's quite comprehensive on the mindset necessary when training a service dog and it goes through each stage of socialization in detail, providing a lot of examples of to where and what things a service in training dog should be introduced to.

I know very little about diabetes service dogs so I can't help on that front, but one thing to consider when you do narrow down breed selection is to consider getting a young adult dog. This is because puppies often change temperament during adolescence, meaning that the perfect puppy can easily not be suitable by the time they're one. It also means the primary checks for hip dysplasia can be done before you start investing time into training. Preferably this dog would be a from a breeder who was intending to show the dog, but when it grew up it had small aesthetic flaws. These dogs are usually excellent because they've already been extensively socialized, and basic obedience skills already taught. But you can also visit your local animal shelter and temperament test many (adult) dogs to find a gem. If you decide to go the puppy route you should get one from a responsible breeder. A popular temperament test to use (for any potential dog or puppy you're considering, not just shelter dogs) is the Volhard test.

In terms of timeline you're probably looking at about two years if you get a puppy, and one year if you get an adult dog with basic obedience skills. That first year is filled with socialization, basic obedience training, and fun-puppy-stuff. The second year is when the diabetic alert training, and public access training can begin.

It's quite easy to underestimate the gap between a well trained pet and an assistance dog. Consider the following scenario. It's thanksgiving day and you have as many people coming over as you do chairs. You have a well behaved pet and during dinner, he eats his quietly and then plays with a chew toy without disturbing anyone because he's a good dog, and if he starts to get overstimulated, then you move him to a crate where he also is quiet due to training. A service dog at restaurant has to deal with many times the people, many times the noise, many more smells, and this time he doesn't get to eat himself, and he can't play he need to lay calmly with his tail tucked in so no one steps on it.
Another thing is what I'm going to call defensive dog walking. Because you're taking a dog to places that people don't normally expect, people are not going to be watching for her at say the grocery store. So beyond a loose leash and heel, you'll want to teach your dog other micromanaged movements so that you can issue a command and she'll move out of the path of the 9-year-old joyriding a shopping cart instantly. A lot of service dog training isn't just making sure your dog can alert you to hypoglycemia, but that she can do it while at the beach and the man an umbrella over is eating a cheeseburger.

And I've said all that, but you mentioned that you particularly what a dog to be able to alert you at night when you're alone and sleep through the alarm. You might consider getting a dog just to be an at-home service dog. These dogs are still allowed to bypass no-pet rules in housing, but they only help at home and thus don't need all the public access training.

To my knowledge there is not one comprehensive book, but I have a few recommendations.

A Dog Who's Always Welcome

The Eyes that Lead

Lend Me An Ear