Others have covered the diabetic part, so i will help with the last question - Vaccination? Yes, you should see your doctor, your wife as well and you will likely need need some shots. You don't NEED them, but going to Mexico and Jamaica and Haiti can result in some fairly serious travelers diarrhea, and there is potential for hepatitis (probably other things as well).
Just remember - Don't drink the water! If you don't see it come out of a bottle yourself, avoid it lol I have heard so many stories of friends going down to mexico, and spending the entire time in the bathroom.