Hello, Sharon!
There are some absolutely wonderful aspects of customer service at Walt Disney World, and catering to Guests with specific dietary needs is among them.
Take a look at Walt Disney World's website, where you'll find a page entitled "
Guest Services: Special Dietary Requests." You can plan ahead and request specific diabetic-friendly options at both Table-Service and Quick-Service restaurants. While the site does state that nutritional information may not be available, it also states that they will attempt to work within any dietary requests as well. Moreover, it's been our experience that at every Table-Service restaurant, the chef him- or herself will come out to talk to our table to closely advise us about our options when dining with a family member with a severe food allergy. They are knowledgeable, cautious and passionate about ensuring that every Guest enjoys a fantastic meal, regardless of dietary restriction.
In addition, a great unofficial source of information for any Walt Disney World Guest with specific dietary restrictions is allears.net. There, click on Walt Disney World, "Dining," and scroll down to "Other Special Diets at WDW." There, you'll find posts from Guests with similar concerns, including how they prepared for their trip prior to departure.
Regarding injections, there is a First Aid Center at each park, which is the perfect place for you to attend to this. Located near the entrance of most parks, these are clearly marked on park maps, and you can easily get directions to them from any Cast Member at any time. I stop into these centers frequently on our class trips, and the Cast Members there are always so compassionate and welcoming, so do not worry!
Send more questions as you think of them. I'd love to help!