Praying.
One of our nieces was born with--or at least it was diagnosed at a very early age--type one diabetes, and they went through similar stresses in getting it under control. But medical science has advanced much in the last few decades and they can do wonders now. She was brought under control and was able to live pretty much a normal life of a kid growing up. And we all rejoiced in her wedding this past year. Her twin brother was diagnosed in his late teens, and though his diabetes was not so brittle and difficult, he too has managed it very well.
But for sure prayer has played a part in all that and so it is a blessing to pray for Saved24's nephew.