Hi and Welcome to YT!
Yorkies are just as healthy as other breeds. They are a little higher maintenance, but can be very healthy. Be sure to google the breeder's name. Research is the key! Ask your breeder about parent screening, health background and pedigree. I've had many phone calls from would be breeders that already have a male or female and looking to purchase one for breeding. I found that if I asked what pedigree is in their background, some will say, "Oh, they are registered" It tells me right away that they know nothing about breeding a quality Yorkie. All they're trying to do is produce puppies. It's a quick way to weed out potential breeders. Your breeder should know their dogs and background inside and out. And Lord forbid there is a problem, make sure the guarantee actually protects you and the puppy not the breeder.
Hypoglycemia is very preventable. They are active dogs with little tummies. They run off their energy very quickly. Make sure they have food available.. and they are eating it in a timely manner.
They are long coated kids forever in toddler mode.
And trust me, you will feel like they are one of your kids!
Good luck in finding your baby, but with a warning.... They are habit forming!!