Will it work in humans? Good question. Here’s a Singularity Hub piece about it:
Scientists have now cured diabetes – at least in a group of dogs – and they used a gene therapy to do it. Amazingly, only a single therapy session was needed to return the dogs’ blood sugar levels to normal. It wasn’t the first time the researchers used the therapy to cure diabetes – they’d done the same previously in a group of mice. But the fact that the treatment worked in the larger canine is a promising sign that it might also one day work in those even much larger animals: humans.